Young hen needs to be reintroduced to flock after recuperating in garage, need help, please.

Since she's been separated from the flock for so long, I would think treating her as a new flock member would be appropriate. Check this article in the Learning forum. You can scroll down to Part 2 and go from there. Since she's been part of the flock and was separated due to injury, not illness, you can skip the quarantine!....
https://www.backyardchickens.com/web/viewblog.php?id=2593-adding-to-your-flock

 

I lucked up for my first few chickens. I can introduce them to anything and they care not one bit. I think it is because their rooster is just so darn docile that his hens are too...I can introduce anything to the original flock and they don't care...but they also continue to ignore new groups of chickens as opposed to the flocks integrating, I have ended up with 2 flocks sharing a space, as opposed to one large flock.