Okay..... I must be honest...
I DIDN'T EXPECT THAT ENDING! O.o
It still makes me shudder while trying to figure out words by words the meaning of all the man had said to her, it's trully a cunning way of narration and gives the thriller (especially all the ambigiousity in underlined/link sentences).
I didn't read The Mouse, yet, but here is my assumptions : a.) the other man He killed at the begining was for their food ration (cannibalism), and He made up the Zed story to cover up his act; b.) He sold out the girl for his life supply; or c.) He trully care for the girl and gives her away to the community to protect her from himself.
And I love how Zed's "no heart nor sense of life in their eyes, I'll do anything to survive", somehow describes the Man egoist, contradicts with his word to "protect you, and protect us" :'(