In the meteor situation, being on the Moon might be preferable if you're in a sustainable environment and you're not in danger of being hit by debris yourself. In this case, it seems to me that you're in a far better position to monitor the Earth and plan a return once the surface is habitable again.

That's a possibility with Mars too, but a riskier return due to the distance.

Let's wait to answer that until we've seen babies born that have gestated in 1/6th gravity.

We know that rats grow OK in orbital microgravity. Doesn't seem like strong gravity is required for mammalian morphogenesis to work.

"As we reported previously (Ronca & Alberts, 2002b), pre- and postflight body weights of dams and the body weights of the offspring used in these experiments were comparable across treatment groups. Within 48-72 hrs following landing, the rat dams that contributed offspring to the postnatal studies gave birth to healthy offspring."

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2610337/