Post apocalyptic work of fiction involving an Wiccan coven?

I was at a pagan gathering recently helping to facilitate an archery class there. One of the people present commented that the gathering and the archery reminded him of a book he'd read recently about a woman who sees her coven safely through an apocalyptic event and how they help to rebuild/reshape society afterward. Would anyone happen to know the title of that book, I'd like to read it.