Make her a coupon book of a variety of things she can "redeem" - Things she can't do or wouldn't ask for. A board game on a rainy afternoon, 2 hours of raking leaves, trimming the garden, weeding, a ride to a supermarket she can't get to, a home-cooked meal, a holiday at your house if she doesn't have family, a ride to the doctor, show shoveling of her walk, taking down and putting up screens (including rinsing them with the hose), dusting for cobwebs or anything else up high (if she shouldn't be on a ladder), decluttering the garage, putting down lime on her lawn, vacuuming the coils behind her refrigerator, putting up Christmas decorations, disposing of her Christmas tree, picking her up if she needs her car serviced (so she doesn't have to wait), a ride to your kids' concerts (if she would enjoy that), a picnic, rides anywhere she needs to go (if she doesn't drive) like post office or bank, or a museum.
If you do a book of 12 items, she'll have one favor or treat per month for a whole year.