Now, you are a wealthy man!

I agree wholeheartedly.
Excellent! The two things I love about this story is one, your Mom is doing well and two, you recognize what you've got. Our Mom's won't be physically with us forever, cherish the time we have with them.
Rams
Yep, both my wife’s parents are gone now, my DIL has lost both her parents at a fairly early age. My son recently expressed regret for not spending more time with my Dad.

When I read the reference to your sister's age I thought, his sister is really old and then I remembered that's just about where I am.

We are blessed.
At a young age I was jealous of our 3 year age difference, not so much anymore! My sister is a CPA and has been working for a garment manufacturing firm as comptroller for years. Due to COVID and not being able to maintain a workforce the decision was made to close the factory by the end of the year. She decided that she might just enjoy retirement.
John, my 91yo mom is in about the same shape. Still driving (her truck). She is an educated, sharp and funny woman (with every one of her marbles). And since her enrollment with the U of MI health care system years ago, she gets top flight treatment, and all her doctors love her and treat her great. This last is particularly important.
I check in weekly or so. Any more, and we run out of things to talk about.
She has SS and dad's pension (spousal shares) and does OK, but I help with her expenses. I just sent her a check for AC replacement yesterday. It said.....
something to help you with your new AC upgrade mom, or just spend it on bad men and hard liquor and have some fun.

I love to hear her laugh.
My mother loves her doctor too and they take great care of her, so important for peace of mind. I love to make my mother laugh too.