The cops were responding to a call about a break-in and when they asked for someone to come to the door they showed up with a gun. The cops aren't going to sit there and wait for the person to start shooting at them. How disconnected do you have to be to think when the cops are banging on the door that it's a good idea to grab a gun and rock up to the door with absolutely no warning?
Did she at any point identify herself to the police? Did she yell out 'I'm the home owner and I have a gun'?
She might get a payout, but very unlikely that anything will happen to the cops given the situation.
The right to bear arms is a lot like the right to free speech. It protects your right to do it, it doesn't protect you from the consequences.