I think it would be better for her, if you brought one of your other ones so she's not alone.
That sounds like a good idea. We currently have a quarantined single chicken in the house and couldn't find her one day when she crawled up to a mirror to snooze next to her reflection. Birds have a flock mentality even if it's only their own reflection. Either get a gentle companion or a mirror for your lone girl. Wildlife rescued a Pelican who could never fly again and by accident they discovered he was less grouchy when he had a mirror to see his own reflection - there were a lot of ducks and chickens and geese in the yard but he didn't mellow out until he saw the "other" Pelican reflection. Flock mentality.
Hens go broody when you don’t want them to… and won’t go broody when you do.

