I agree with @azygous. Combs don't "grow back", but sometimes the injured part can heal reattached if you can get it to stay long enough. They do tend to heal relatively quickly, so fingers crossed. If it doesn't heal that way, then based on your picture, I would probably dub it. If it remains hanging like that it's going to interfere with her eating, drinking, and possibly vision, and be more prone to being re-injured.
she gave Pidgey lidocaine for pain and silver nitrate to stop bleeding. Dubbed it and gave more pain med and antibiotic. She is much better and will have the small coop to herself when she goes back outside. Currently she is hanging out in my dogs soft kennel.
