I'm not seeing any pin feathers coming in to indicate a molt, maybe they are just not showing in the pictures you posted. My first reaction was also rooster damage, but the wing areas look to be a little lower than what you usually see there from roos. Dominant hens will also sometimes do mounting behavior especially in the absence of a rooster.
Couple of questions, how many birds total do you have, ages, and how much space do they have when roosting at night? I'm suspecting that they may be a bit crowded and she's likely low in the pecking order and this may be happening during the evening battle for roosting space. Once blood is drawn the pecking will just get worse as they will mercilessly go after the red, raw, bloody area. Even the most peaceful flock can sound like major battle when it comes time to claim their space in the coop at night. So if that's the case then while she is isolated to heal I would try to remedy that if possible. Not having enough space is often the cause of things like this. Sometimes just adding roosts or putting them at different heights will solve the problem. Or putting up a divider so one side of a roost is kind of blocked from the other will help. If you post pictures of your set up it would help you get suggestions. It does look like bullying and pecking wounds to me, so that's my best guess as to what is going on.
You do need to keep her separated until she's healed enough that they won't go right back after her wounds, and if there is still redness you can try using something like blue-kote to hide that until feathers come back in. If she isn't molting or it's late in the molt those feathers may not come back in until the next molt.