I keep thinking of the character in Lucifer's Hammer that buried a set of The Way Things Work in his back yard before the meteor hit, so that when the initial disaster had subsided, he could go back and dig up all the volumes to help rebuild society. Of course, in that story he had time to prepare for it, but I don't think you need a truckload of books to set up a serviceable and self sustaining village. A relative handful to establish yourself after the chaos ends, and then you can branch out for more. And the survivors would probably be learning new skills at a crazy rate (or they would die). Naturalists and jacks-of-all-trades would probably do well.
And I would bet that a government like the USA probably has all kinds of contingency plans for a widespread and lasting blackout to ensure the preservation of the core government and strategic places to retain control over.
I thought of the same book (Lucifer's Hammer, that is). Didn't he also store a lot of other well-needed books, info, and items?
One thing that likely is correct about this show is the relative lack of older people. People on meds, old or not, would not survive. Not talking vitamins, but diabetics, thyroid, some cardio, etc. I know I'd be gone (hypothyroid, I'd sleep myself to death). And those left ARE relatively healthy. They'd have to be, because there's little to no meds, certainly not enough to sustain 15 years.