The thought comes to mind that perhaps your Mom is going thru the change of life which all women go thru. Rapid mood swings are one often symptom. Perhaps she could see her physician to be sure there aren't any medical conditions contributing to those mood swings and if there are, she could get some help.
At the same time, be honest with yourself and be sure you are not being confrontational with her. Maybe doing something nice and unexpected for her occasionally (perhaps including Matt) would help.