Prolapse. Now what to do with the one hen left?

Hello, this is my first post, although I've been reading this website ever since I began my flock 5 years ago. Everyone here seems to know a lot about chickens, and I'm hoping you might be willing to take a moment to give me some advice.

A little over 5 years ago, we started our backyard flock of 5 hens (barred rocks and rhode island reds). They free range throughout my small backyard, eating a lot of bugs as well as the food I provide. For the most part, it's all been easy with no problems at all.

Two years ago, two of the hens became ill and died a couple days later. I have no idea what happened, but it only affected those two and the remaining 3 hens continued to do well. About a year ago, a stray dog got into the backyard and killed one chicken (I saw it happen and was fortunately able to stop the dog from killing the others).

Other than these two incidences, we've had no other complications or difficulties with the health of our flock.

So, for the past year, I've had only two hens that are now a little over 5 years old and still lay consistently. The two of them are constantly together, and I rarely see one without the other right there by her.

Yesterday, we had our first major complication-- I discovered a very large prolapse in one hen. We tried our best to treat her with all the advice from this website and from YouTube videos, but it was a mess. She was full of maggots which we tried to wash out the best we could. There was a huge cyst/abscess hanging out of her about the size of a small egg (we lanced it and clear water came out of it).

Anyway, we treated all this to the best of our ability, following all the procedures we read. We kept her in a cage overnight. This morning when I went to check on her she was lethargic, hot to the touch, and had no interest in drinking water. There are still a lot of maggots, so we obviously didn't get them all.

I'll check on her throughout the day and continue to treat her, but my husband and I are assuming we'll probably have to put to her down when he gets home this evening.

My concern now is for my remaining hen. Will she be happy without a flock? They've always been a close knit group, and I've never seen this hen alone. Should I continue to keep her as a single chicken? Is it more merciful to put her down too rather than have her be alone? I don't want her to be unhappy, so I don't know what to do.

My husband and I had already decided to care for this flock for as long as we could, but we planned to not replace them after they're gone. Having a flock was fun and we love our backyard birds, but we don't want to keep doing this long term. For one thing, we just don't need that many eggs any more, now that all our teenagers are grown and out of the house. Plus, it's been heartbreaking every time we've lost a hen, and I don't want to go through that again.

 

We don't mind keeping her and caring for her for the rest of her life, if it's okay to have one single chicken. We do care about her very much-- that's why I was wondering if she would be too miserable alone. I want her to be happy (and I'm heartbroken that one of my chickens is so ill right now).

I do have friends with flocks, and I might be able to rehome her. But, do old chickens integrate well into other flocks? That just seems really stressful for her to get used to new surroundings, be picked on by strange chickens, etc.

I guess I'm wishing I had a crystal ball and knew what would be best-- keeping a single chicken or re-homing her. That's what made me wonder if it was just more humane to put her down with her sister. But, she is healthy and there's no reason for it other than I don't want her to emotionally suffer.