The Covid excuse won't work any longer. They could have returned several years ago.
Options as I see them:
1. Board a plane and return to the US ASAP. Do not sign an I-407 if asked to do so. Hopefully, CBP will not refer them to an Immigration Judge.
2. Voluntarily surrender their Green Cards by submitting an I-407 from India, then reapply for immigration or visitor benefits.
If they want to live in the US, I would try #1 first. Other members might feel differently.