I love my gardens, I'd not be persuaded to move.
Perhaps, faced with a move she'd accept a cleaner, gardener, and some frozen prepared meals (I doubt I'd like that sort of food, but needs must).
As we've aged (we're around 80 and 82) we do find some tasks in the gardens more difficult - for example we oversee shrub planting and no longer dig enormous deep holes. We want the gardens as we want them - overseeing is key.
We have the exterior of the windows cleaned, only do insides now. I sweep and clean daily (dog hair), but we have cleaners in for the fiddly bits that are becoming harder on our knees since TKR. We recovered quite well, but knees of floor hurts, even 6 years on. All that to say, we still ski, travel long haul, take quite long walks, but we choose to save ourselves for what we want to do.
Kindly explain some options for staying put.