When you get to the very late years of life, the world becomes much smaller. I notice that with the 90+ crowd that I know. Their worlds have become smaller in terms of people and places due to issues related to physicality, driving, mental acuity, finances, and more.
The little things can make a big, positive difference for people at this stage of life. Little things related to their physical surroundings and home, health, routines, outings, and needs.
With regard to physical surroundings, of course, a comfortable place that has what you need is ideal for the later stage of life. Places that are too crowded, uncomfortable, and physically challenging do not support ideal aging.
A good routine is ideal for people at these late ages--a routine that includes regular meals, rest, and entertainment to keep life interesting. Well-planned, thoughtful, just-right outings make life more interesting at any age, and this is true for your nineties too.
To be as healthy as you can be will also assist the aging process. Understanding what "good health" means for you is important; and making healthy choices before you reach that age will definitely hep you at that age.
If I'm lucky enough to live to my ninth decade, I want to be prepared with a lean home, good routines, healthy living and the kinds of interests that survive the aging process.