Usually I'd suggest trying to get her off of Purina and the grocery store foods, they aren't the best quality, but since she's old, a huge diet change may not be the best idea.

I'd suggest trying a food that firstly has no chicken in it - that can be a common allergen that would cause excess shedding, coat issues and vomiting. If that doesn't do the trick, then try removing fish (my cat is sensitive to fish and will vomit if she's given kibble with fish in it) and then if that doesn't do the trick either, I'd suggest trying a grain-free food because it could be that her body is not processing the grains, hence the vomiting.