Like what?
People have been suggesting that he aim for the leg or shoot in the air, both of which were not options.
The only other suggestion I heard was him using a taser. I don't know enough about tasers to say whether he could have hit her from that range and put her down before she managed to attack. That might have been an option, but I'm betting police protocol is to use deadly force when you believe another person's life is in danger.
No one's debating whether she should be here or not. We all believe she should be alive right now.