Whats wrong with my mom...how can i help her?

I don't think it's due to money but more of a depression, time are tough at the moment with economical issues and finances, perhaps she believes that she is going to become poor with having to support you and her both, and a family perhaps on top of that? Perhaps she is feeling lonely, people like that tend to keep to themselves and eat when upset. Try sitting down with her and talking about it; try going over the reasons you guys are arguing and why she is so very negative and strained. Work out days on which she will clean the house while you get some free time. Try spending time together.