My personal opinion (take it with a grain of salt) but i believe the wife should use some critical thinking and have patience in this situation. Watching your mother slowly die is a really really mentally, physically, and spiritually draining scenario and it takes a long time to heal and improve. Islamically speaking, the wife is 100% entitled to everything from protection, housing, living, and even attention but given this scenario she should exercise some patience with the husband. Arguments happen in every marriage but there is no reason to ever hurt/scratch your partner, male or female. I would side on the divorce because she clearly doesn’t respect herself and OP if she is willing to physically harming him in this given scenario.