It was most likely a hernia then. There doesn't seem to be enough blood to suggest that she was attacked by the other hens severely enough to cause her injuries.
Does the run have a covering? It's possible she was gashed by an aerial predator like a hawk, and the roo chased it off.
It unfortunately seems more likely that she was injured and the roo/other hens attacked her, however.
Also, I hate to ask this of you, but can you see where the intestines...
Is that orange loop her intestine? Do you have roosters?
It looks like she was attacked by something a disemboweled. Is it possible that she collided with something sharp in the run?