Yes, it's not so much a clear answer as a "well, this is the best of a bad set of options." I assumed basically from page one of this book that we were heading for a scenario where the kid would have to make the painful decision to "fix" the problem instead of burning it all down, despite her completely understandable inclinations. And I like that her desire for destruction isn't just a function of her youth -- there are notable adults who would have completely agreed with her. But the decision she makes seemed inevitable to me. That's part of the point, I think -- that the people who have arguably paid the highest price and suffered the most are the ones who have to stand up and make the hard call.

I contrast the ending to that of The Girl With All the Gifts, which, spoilers, comes down on the other side. The burn-it-all-down-we're-all-fucked-anyway side. Though in that case there isn't as much blame to go around.