That's a difficult thing to say really. 'Guns save lives' If the man that broke into your house made a move to attack either you or your mum then i'm sure she would have blasted him away, in which case the gun would have killed someone else. Or in this case couldn't you say that she scared him off to a different home where he killed. So in this case everyone would have needed a gun to be safe because he seemed so determined to kill. Obvously everyone having a gun wouldnt prevent crime, just make it worse. It sounds like this man was slightly crazy as if I had a gun pointed at me I wouldnt think twice about having the risk of it happening again.