Question: Who is Empress Mao (Ming)'s mother-in-law?
Sentence (from "Cao Rui"): On his deathbed, he entrusted his son Cao Fang to the regency of Cao Shuang and Sima Yi — a fatal mistake for his clan, as Cao Shuang monopolised power and governed incompetently, eventually drawing a violent reaction from Sima Yi, who overthrew him in a coup d'état (Incident at Gaoping Tombs) and became in control of the Wei government from AD 249, eventually allowing his grandson Sima Yan to usurp the throne in AD 266.
Relevant evidence: No