This is a tough situation and you're doing a really good job. HE is doing a SUPER job of resting & recuperating! While I initially thought concussion, too, & still think he has one, I was wondering if she might have cracked his little skull and or a bone in his neck. (Rhetorical, as there's no real way to know.) The pupils reacting to light is a good sign & it seems like he will come out of this, thankfully. Their bones can knit together quite well & I think that if he did indeed suffer a skull fracture, he is seemingly on the mend.
Sorry about your little Foghorn's troubles. He is a very handsome bird & he's definitely responding to you & all of your efforts. If you two weren't bonded before, you sure will be now!
As for you Mother & that broom: Some day, you'll have a place of your own & won't have that concern. You'll have other concerns, I'm sure, but someone clobbering a bird won't be one of them.
At least she's helping to nurse him back to health, so there's that... Oh & I'm thankful for your cousin, his help & experience with chickens.