Poor sweet girl

Do you feel comfortable "putting her out of her misery" or do you typically just let a chicken pass on her own?
I just read through the thread. I am no expert but between her age and the symptoms I have read, it could be her time.

This seems similar to what happened to my production layers (Golden Comets). They just declined and I tried everything but they eventually stopped moving around, then stopped eating, then stopped drinking. Same green poop the whole time. We ended up putting them out of their misery (humanely) because it was hard to watch them suffer. But I absolutely understand that some people cannot do this and would rather just make the hen feel as comfortable as they can.
Whatever happens, I wish you and your hen the best. It's so difficult when this happens.