My daughter is 14 years old she got menstruation 5 months ago, 2months ago she diagnosed lower lumbar 20degree scoliosis, what is the best treatment?

Follow . Isolated lumbar curve is a bit unusual. May require further imaging based on history and exam. 20 degrees is not a very large curve provided there is not too much vertebral rotation. Most girls have had their peak growth spurt by the time they get their period. So there may not be that much growth left and her 'risser' grade may give more clue to that. Surgeon should follow w films.
Well, you are talkin. About 2 seperate things. If her menses are problematic then she can get on the birth control pill. The scoliosis, though, i'm not sure about but the menses did not cause the curvature of the spine, good luck.