13th level Humanoid that's able to evade a 18th level party? That's a decent CR gulf to span. Classes alone probably won't do it, since classing something to level 13 means it should be balanced against other 13th level creatures, though min/maxing with an emphasis on evasion might slant that.
As a magic item suggestion, give the NPC a unique Artifact of your own creation that gives them additional evasive powers; probably something that locks to their person so high level PCs can't just snatch it from them to make them powerless. If you want them to just be hard to nail down, have it grant etherealness or earth glide (if underground a lot). If you don't want the Artifact to be a loot item the PCs get afterward, you might try something from the Weapons of Legacy supplement, where the item in question is an item that has quests/requirements to use it to its full potential, and the NPC has done the quest(s) but the PCs haven't/can't.
For the Lycanthrope aspect, normally a Lycanthrope build has to use an "animal" as the base creature type. Can you have this NPC through some means be a non-animal lycan with additional abilities? Create a Lyncanthrope build for a Displacer Beast or similar hard-to-nail-down beast; then the NPCs evasive abilities are intrinsic.
For your players' specific choices:
P1 has the right idea by picking a SAD class in the Druid, but has his dump stats off kilter. While dumping Strength, even down to 6, can be managed (especially for a Druid who should be able to travel light, as Druid defensive buffs are excellent and they are well-equipped to not need tons of rations, etal), he shouldn't put his racial +2 into it.
Given his array, I would have him dump Strength and Charisma -- Dexterity is needed for initiative, and Intelligence for skill points, so you can't dump either it turns out. Wild Shape is also more beneficial for P1 than he thinks -- Natural Spell comes at the same level as Wild Shape itself in PF, so he gets casting-while-shaped essentially "for free".
Along with that, he should put that +2 racial bonus into Wisdom and bask in the glow of a +4 starting Wisdom bonus.
P5 is also on the right track with focusing on archery -- the casting of the Ranger is not strong, and with two full Vancian casters in your party (namely, the druid and the wizard), his casting won't be needed for much, while the Dexterity-based skills will be quite useful in a rogue-less party. Furthermore, his choice of Charisma for a dump stat is a reasonable one -- it's not nearly as severe a dump as in P1's case, and many Rangers don't rely upon Handle Animal the way Druids do.
Regarding concerns about healing
Having played a Druid in a party where that was the sole access the party had to healing magic, by the way, I would strongly recommend your party obtain Wands of lesser vigor if you are willing to waive the [evil] descriptor on the spell or Boots of Earth (if Fast Healing 1 is enough) if they aren't, and give one to the druid and one to another character -- Druids can't convert to healing spells as they get Summon Nature's Ally instead, and spell slots are precious especially at lower levels.
In general:
You are right to be somewhat concerned about this...
The more relevant sum in this case is of attribute modifiers -- if it's less than 0, D&D 3.5e (and presumably PF (Pathfinder) as well as it's derived from D&D 3.5e -- if it's not a rule there, you can always port the 3.5e rule to your game as a houserule) has a rule that allows the player to reroll for their stat array.
In your case, it comes out as follows:
- P1: +3, +2, +2, +0, -2, -3 = +2
- P2: +3, +2, +2, +2, +1, -1 = +9
- P3: +3, +2, +2, +1, +1, +0 = +9
- P4: +3, +2, +2, +1, +0, -1 = +7
- P5: +3, +0, +0, +0, +0, -1 = +2
Which means that all of these arrays are acceptable, at least by the sum-of-modifiers rule; however, the +2 arrays are indeed non-trivial to work with.
However, character class and construction has much more to do with this than ability scores alone.
Character classes and builds in D&D generally depend on one or more attributes to do their job:
- For a Fighter, this is either Strength or Dexterity, but Constitution also helps
- Rogues are all about Dexterity, and can make use of Intelligence and/or Charisma
- Clerics and Druids rely highly on Wisdom as it is their casting stat, but also benefit from Strength and to a lesser degree Constitution.
- Wizards are all about Intelligence, but are helped a bit by Dexterity as well
- Sorcerers rely on Charisma and also receive a little help from Dexterity
However, not all classes are this simple, or Single Attribute Dependent (SAD). Some classes, unfortunately, are Multiple Attribute Dependent (MAD), which means they have features and functions that key off of different attributes:
- Rangers rely on Wisdom for their casting, but need Dexterity heavily for combat and benefit from Constitution and/or Strength.
- Paladins are equally troublesome, as they need Strength (or possibly Dexterity) for their melee combat while using Charisma for their casting and paladin abilities. (PF actually fixed the worst of this -- the 3.0/3.5 Paladin used Wisdom for casting, which was terribad as it meant the character had to have 3 good attribute scores at a minimum.)
Furthermore, some character classes can afford to "dump", or take a penalty in, certain stats:
- Fighters can generally dump Charisma, as they aren't expected to negotiate their way out of situations
- Wizards often dump Strength, as they aren't getting into frontline combat
- Clerics and druids will frequently dump Dexterity, especially if they aren't using ranged weapons or have Zen Archery -- that feat also allows for SAD archer Rangers, relying entirely on Wisdom.
Overall, this means that P1 and especially P5 must be more careful with how they build their characters. P5 is going to have to go with a fully SAD class with an easy dump stat, for instance -- if they're dead-set on a Paladin or two-weapon fighting (aka dual wielding) Ranger, I'd let them reroll because it's not compatible with their stats array. However, that array would make a reasonable Fighter, Cleric, or Druid.
P1 is a bit more interesting, because they have a double dump on their hands -- most classes only have one designated "dump stat". It is still possible to be effective with two stats dumped, even as severely as that array dumps them, but it takes care to avoid backing yourself into an unexpected corner by dumping the wrong stat. (Dumping Intelligence, Constitution, or even Charisma can have unexpected side effects in certain games -- it may be the case that characters with a low Intelligence will not be able to speak properly, low-hit-point/squishy characters will have trouble surviving first level, or a particularly uncharismatic character will be run out of town before the adventure can get off the ground.)
Footnote: these lists are incomplete -- I don't have experience with all the 3.x or Pathfinder core classes
Bonus: Racial bonuses shouldn't be used to "fill holes"
As to P1's racial attribute bonus? It should go to the dependent attribute for P1's build, not to fill a "hole" in their attribute scores -- you're basically always better off putting it in the strong suit, especially with a +2 bonus because that translates into an unconditional +1 to the derived modifier.
Best Answer
You appear to be using a sourcebook from the wrong edition of D&D.
Based on your comment that you used an outdated version of the Player's Handbook to create an eladrin player character, and that it was rejected by three seperate DMs, it appears that you are attempting to use the D&D 4th edition Player's Handbook to create a character for a D&D 5th edition game.
You can't do this. D&D 5th edition characters can only be made with the D&D 5th edition rules and sourcebooks. The two rulesets are incompatible.
This is particularly important between 4th and 5th edition, as the rules changed so much between these editions of the rules that they're almost entirely different games.
For reference, the 4th edition Player's Handbook is the one subtitled "Arcane, Divine, and Martial Heroes". The front cover depicts a yellow-green lizardlike dragonborn fighter and a female spellcaster with a staff, and the book is credited at the bottom to Rob Heinsoo, Andy Collins, and James Wyatt.
In the earliest editions of D&D, particularly Advanced Dungeons & Dragons 1st and 2nd edition in the 1980s and 1990s, it was common for players to mix-and-match content from different editions of the rules in this manner. However, this practice is no longer commonplace, since rules now change so much between editions.
I recall a player in an online D&D 5th edition game I ran making a similar mistake. First, he attempted to play a psion, which turned out to be a fan-made content from dandwiki.com that he had mistaken for official. When I rejected this, he attempted to create a tiefling, but did not actually own the Player's Handbook, and used Google to find a D&D 4th edition D&D Insider PDF article of optional tiefling powers, which he mistook for 5e core rules and promptly added to his character sheet.
As KorvinStarmast's answer notes, however, you can play an eladrin ranger in D&D 5th edition; you just need to use the 5th edition version of rules to do it (in Mordenkainen's Tome of Foes or the Dungeon Master's Guide). Note that if you happen to play in official Adventurer's League groups, there's a limit to how many sourcebooks you can use to build one character. If you're not too attached to the eladrin and don't have access to these other sourcebooks, it may be simpler just to play one of the types of elves in the D&D 5th edition Player's Handbook.