"Marital ancestor" must be your wife or husband's ancestor, right? So, the pointy ears guy's wife is connected to someone who knows Yang Kai or at least the world Yang Kai is from. Though the demons had pointy ears, but those demons in the closed world should have nobody, aside from the coffin zombie, in the outside world, so Cang Yan most likely isn't talking about anything demonic, despite his pointy ears.