Get her any of the classics+zombies/seamonsters/vampires, etc, books. Sense and Sensibility and Seamonsters, or Pride and Prejudice and Zombies, or Jane Slayer. Classics with a funny new twist that any granmother can enjoy.
Get her a book by Alice Munro (Grandma-age Canadian author, one of the best short story writers ever). Excellent writing, not sex-free, but it's the kind of sex Grandmas might approve of or at least understand.
The Unlikely Pilgrimage of Harold Fry by Rachel Joyce
Unfamiliar Fishes by Sarah Vowell
And pretty much anything by Dorothy Sayers.
Unfortunately there isn't an audio recording of Naomi Wolf's Vagina yet, so I got nothing.