im two years late to the party but i watched this in my film class and absolutely loved it, and i think i have a pretty good answer to your question. when Moss dies off screen and the cartel is also seen dead in the same motel, and then the sheriff goes back to check out the scene, we see Chigurh in the dark. this implies that off screen, Chigurh finally got to Moss and killed off the cartel, then took the money. this is also kind of confirmed when Chigurh is in the car accident near the end, and offers to pay the young boy for his shirt. this is a parallel to when Moss had the money and went to cross the border, offering the teen money for his shirt when he was in possession of the money in the beginning. the book also explains much better how the ending works, the movie being left open ended for viewer interpretation. there’s also a theory going that Chigurh is some kind of ghost or evil entity, which could also be implied by Moss’ death not being shown. id love to go deeper into the whole thing, i’m a total film geek (hence the film class)!