Who feels responsible for Reuven’s death?

Hannah feels responsible for Reuven's death. She tells Commandant Breuer that Reuven's mother is dead and says "no" when he asks if Reuven was her brother. With no family, Breuer felt free to take Reuven, there and then.

When Reuven didn't answer, Hannah stepped forward. "Please, sir, his mother is dead." Rivka gasped. Hannah heard her and added hastily, "She died years ago, when he was born." The commandant stood up and stared at her, his eyes gray and unreadable. "Are you his sister?" She shook her head dumbly, afraid to say more.