I don't plan to be stranded on a desert island, but my zombie apocalypse novel would probably be a book by Elizabeth Peters, one of my ultimate comfort read authors. Mummy Case is the first book in the series in which Amelia's perniciously precocious son, Ramses, finally gets to play a prominent role. Considering the book also includes a peculiarly peripatetic mummy, an opinionated cat, and some rather amusing religious lunatics, it is the perfect book to cuddle up with while the zombies throw themselves fruitlessly against my quadruple-bolted door.
I reviewed it here, and reviewed the first in the series here.