What is the ruling on a young man who broke into his neighbor's house, forcing the neighbor to kill him?

It is not permissible to kill a thief or an aggressor unless there is no other way to repel them except by killing. The thief died committing a grave sin, and he is exposed to the warning [of punishment], for if the thief is killed, he is in Hellfire, based on the hadith: "What if I kill him?" He replied: "He is in the Hellfire." This does not mean his eternal damnation in Hellfire, as the اہل السنة (Ahl al-Sunnah) have unanimously agreed that whoever commits a major sin and dies upon monotheism will not remain eternally in Hellfire. Rather, Allah may forgive him out of His grace.