I can’t find the last Nekker Nest. Does anyone have their locations pinned on a map

Here is a video showing exactly where she is. It's easier to just watch the video to find malena but basically go away from the waterfall along the path leading back to the village, then make a left along a SHORT path, then make a left again on another path that heads south west sort of. You'll see a cut scene with some guy asking for help, then you fight some monsters, keep going up by the broken wall after you fight them, she is hiding behind the wall, watch out for the traps.

The laboratory is in a cave, and the entrance is nowhere near the marker on the map.

Exit town along the south-east path.

Go left, toward the big rock face.

Ta-da! Cave.

This is the location of the cave entrance on the map.