Answer:
Not enough context to select best option, but I have provided translations below
Step-by-step explanation:
Passé composé:
Nous sommes rentré à minuit.
(We have returned/returned at midnight)
Imparfait:
Nous rentrions à minuit.
(We returned/used to return at midnight)
Is it immediate past and 1 occasion or distant past and/or a habit? This could help for context