Hi,
i'm 48 & had a hysterectomy at 42 but I still haven't actually gone through "menopause" so I wouldn't assume that your mum is going through it.
Her symptoms could be caused by many things, certain illnesses, vitamin/mineral deficencies, stress, other emotional stuff (including maybe having her child/children growing up & leading their own lives so what is she supposed to do now? - many women - even if they work- go through these feelings).
She needs a complete physical, temp, pulse, blood pressure (kidney & liver function tests, cholesterol, sugar levels) also eeg (brain) this would show stress levels by showing serotonin imbalance.
In the meantime though try getting her to eat foods high in tryptophan (search on-line for natural sources such as turkey, nuts, yoghurt some cheeses & nuts etc). Also does she have a life of her own? Any interests outside the family? Introducing these (if they're lacking) could be a big help. Plus as a mother, it makes us feel great to know our kids care. If you live at home try & watch some tv or go to a movie with her & talk about your lives (hers as well as yours) if you live away from home, a phone call, a letter a small "gift" just out of the blue. The "gift" can be just a cutting from a newspaper about something you know she's interested in with a message from you saying you thought she's like to read this or you saw this & thought of her.
Whether she's sick or stressed some attention (tlc) will definitely help.