What do you buy for your mother-in-law's birthday?

Wealthy. Tiny, crammed apartment. Picky. Inscrutable. Bold. Opinionated. Eighty. What, exactly, do you buy for your mother-in-law's birthday? She has everything she wants, and has specifically asked not to be given gifts. So we sent her flowers, figuring they'd be lovely but temporal. Now, hubby wants to bring something for her to open at her party...a good urge, but we are both at a loss.