Causes of vaginal bleeding in menopausal women?

Many possibilities. Many postmenopausal women will have minor break through bleeding, but if it continues or worsens, you need to see your gyn.
Several. There are several different causes including a growth such as a polyp on the cervix or in the uterus, taking hormones, lining of the uterus that needs to shed, abnormal cells on the cervix or in the lining of the uterus, for example. The cause needs to be identified. Please see your doctor.