how and why are Hassan and his wife killed? chapter 17

After Rahim left Kabul, word spread that a Hazara family was living alone in Baba's house. One day, the Taliban came to the house and demanded that they leave. When Hassan protested, they took him out to the street, forced him to kneel, and shot him in the back of his head. Farzana ran out screaming and they shot her dead as well.