Thanks for sharing these thoughts. I think the guilty feelings your friend has about not wanting to visit her mother is not because she doesn’t want to, but perhaps it’s more so the avoidance of negative emotions she gets when seeing her mother in the state she is in. That, too, is normal. I don’t think she should feel bad either.
As for you not wanting to see your grandchildren, it reminded me of how my in-laws have straight up rejected my kids for sleepovers because they’re too intense lol. But I know they’d do anything for them :)