My widowed mother

My mother has been a widow for close to 18 years, and the bitterness from this has made her a relative recluse. My sister and I are very socially active, whilst also being academically solid. However my mother has very scary tantraums during which she cries and screams for hours at a time, for relatively small infringements like meeting a friend. I love her, but her tantraums are becoming impossible to deal with, and the only other option she seems to be leaving is, for us to have NO social life whatsoever. What can I do?

She is the only one who can change her life. If she doesn't want to make the effort, nobody else can do it for her.