From what I'm reading, she's been at the gramma's house for a little bit now, is getting overfed, and threw a fit at some point, and now you are worried about her health. Is she colicking, if so, call a vet asap, if she's not then the fact that she's moved and no longer getting that much hay should prevent any issues from the over feeding. I would have a talk with the gramma, or even involve a vet that can tell the gramma how unkind it actually is to overfeed a horse, especially alfalfa, and hope that she gets the hint before one of her horses ends up having serious issues. Plus it will also save her money if she stops feeding her horses that much food. I hope that your friends horse is okay, and it sounds like you guys took the first big step in getting her to a different place that won't be overfeeding her.