Looks like she's been plucked by her flock mates. She should be ok, just keep it clean and put some sort of pain relieving ointment or spray on it. There's a balm at Walmart called Dr Jeff's all purpose pet balm, or something like that, it's in a square tin in the pet isle and it works really well on any scrapes, cuts, or skin irritations your animals might have.
Hens go broody when you don’t want them to… and won’t go broody when you do.