If necessary, to the death.
A man and wife fought an intruder to protect their home and young child. They fought like they should fight. Violently, without pause and with all means at their disposal. The husband fought with the intruder while the wife retrieved a knife and stabbed the intruder to help her husband. That takes a lot of mental strength.
A firearms instructor once told me to: "Fight, fight, continue to fight. If you die, you make sure the attacker dies first so they will be your servant in Valhalla." That is a smart plan.
Would they have been better off with a firearm? Of course. But that didn't stop them from fighting for all they were worth.
Lessons: keep the door locked, even when you're home. Be paranoid when opening your door to unknown people.
Oh yeah, and always fight.