Ooo, we're talking rich people money!
Then I'd buy a brand new car, the hell with the value dropping the moment you drive off the lot.
Get mom a suite at one the really nice assisted living places. The ones that do the chief quality cooking and have one to one help and great on site medical help. She's in her late eighties and deserves some pampering.
Pay off my daughter's mortgage and buy her a new car too.