I thought of both of the same items and then viewed the other posts: a real Tiffany item (earrings, bracelet) of a few hundred dollars, and a DVD of the Breakfast at Tiffany's movie and any other Audrey Hepburn movie (maybe the Fred Astaire classic) but maybe not the scary dramatic one (I think it's "Wait Until Dark"). If you think she has these already, give her a gift certificate to Amazon with a note that you hope she'll buy what she doesn't have.
You could also give her a biography of Hepburn - not just her movie career but her charitable work.
Or you could make it really "breakfast" oriented with some high end coffee, a tea assortment, a really good oatmeal or pancake mix, and some all natural sweetener like stevia, maybe a gourmet fruit spread (you can find a lot at farmers' markets now, made right from the ripe berries from their bushes).
And if the kids are old enough, have them draw a picture or write a thank you note.