Final answer:
The most common cause of post-menopausal anovulatory DUB is endometrial hyperplasia, which is diagnosed through an endometrial biopsy and treated with hormone therapy.
Step-by-step explanation:
The most common cause of post-menopausal anovulatory dysfunctional uterine bleeding (DUB) is endometrial hyperplasia. This is a condition where the lining of the uterus becomes thicker than normal. The diagnosis of endometrial hyperplasia is usually made through an endometrial biopsy, which involves obtaining a small sample of the uterine lining for examination. Treatment for endometrial hyperplasia typically involves hormone therapy to regulate the hormonal imbalances that contribute to the condition.