Check and see if you can remove the object. Be gentle and don't so you don't cause worse damage. If you can't get it to come out It could be a prolapse rectum and not just a bloody stool. You are going to have to look closely at it and if it is tissue and there is no vet tonight to get a hold of you will need to push it back in. I think I would find a vet some where close by that can provide care for you kitten. I think this would be very hard for a laymen to do. But if it is her rectum that is sticking out it need to be put back in so the circulation is not cut off to the rectum. And secondly she will need a surgery to fasten every thing back where it should be. Try to find a 24hr vet clinic/hospital. Even if it is a bloody stool you kitty needs to be seen for the blood in her stools. I hope this helps.
You should call your vet right now. That could be a prolapsed uterus (which is common in cats).