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.
