The opposite of 'lock' is quite clearly 'unlock'.
But what is the single-word opposite of 'lockdown' ?
The family were relieved when the time came to _________________.
EDIT : The comment is noted that this looks for a verb.
I would also accept a noun in the following sentence :
The family were relieved when the time came for ________________.
Best Answer
Some people in the UK and India have been using the word "unlockdown" as the opposite of lockdown.
For example, see this Sunday Times article on "The Great Unlockdown", referring to reversal of the lockdown that had been imposed due to COVID 19.