Yeah, that looks exactly like a scab, even if someone is not picking on her, if it is irritating her, she could very well be even scratching it off herself. Might also check feeders/water containers for anything she could have initially scraped her head on, and keep them from sticking their head though fences to get things on the other side. It doesn't look abnormal or anything, just looks like a simple comb injury. You can put on some antibiotic ointment if you wish, but it should heal over time as long as the wound doesn't keep getting opened up.
