The same issue as pms fluctuating hormone levels alter persons mood.
It is all due to harmonal changes.
Do not worry.
Menopause last about ten years yes thats right suggest some extra estrogen for while will also feel better.
You get that way because of your hormones. You aren’t producing as much and it wacks you out more ways than one.
It is called moon swings, and its “Mental pause” with power surges! and yes 7-10 years. We get depressed too. Be patient she needs to get on something. If no HRT, try Omega-3 vitamins ot flax seed oil, they will help with her symptoms.