My mom keeps getting hot flashes from almost 12 yrs and she is 58 yrs old now. What woud be the right treatment?

Hot flashes. She should see a doctor first to rule out other conditions that mimic menopause. If nothing else is found she cand try hormone replacement therapy if there are no contraindications.
She has options. She may try over-the-counter soy supplements with a reasonable success rate of 30-50%. At 58, depending on medical and family history, she may be able to take a very low dose of estrogen (and Progesterone if she has a uterus) for a few years with a minimal increase in the risk of breast cancer, heart attack and stroke.