I would sepearte her inside a dog crate. First though, get her cleaned up, and a soak in warm soapy water will help. Epsom salts can also be used instead. Another picture later might be helpful. Put some honey or mild oil on the prolapse tissue as long as it remains outside. Honey or sugar and a couple of drops of water can help shrink the tissue. Just don’t let the prolapse dry out. If her insides come out, which can happen in a severe prolapse that has been pecked, then you could think about euthanizing her. Unfortunately prolapses and vent pecking can damage the vent later on. Prolapses can occur from a lack of calcium, laying too large or soft shell eggs, being overweight, and dehydration. It can take days for a prolapse to stay in, but I would keep trying to push it in and hold it for a few minutes while holding her in your lap on a towel.