I keep hitting this elder care issue in part because I get a lot of pushback. It really is one reason why electeds try to hang on so long, and this has been privately confirmed to me by staffers.
Unless you are a rich person (common in Congress) who has had a private staff for years (much less common), there is no way that you can buy the kind of care that a member of Congress can get.
Elder care doesn't mean "wiping your ass." It isn't medical or nursing aid care. It means handling your basic daily affairs, mostly.
One difficulty with a private staff is you have to manage the staff. The United States Congress is an employer that handles most of the staffing issues. You also have eager overeducated people willing and able to put in extra effort, to put up with shit they wouldn't from other bosses.
Sure a rich person can hire a staff, but that's hard and they mostly won't be the Ivy grads who chuck their CVs at your office constantly.
If you do have money, you can plan for these things, but for these people, this was their plan.