Xu Ziyi and Xu Sheng left with their father, who had been reanimated from the pollutant earth.
It might sound like a hell of a joke, but in fact, this is indeed a hellish joke. A big reason Xu Xiao's spirit couldn't rest was that his body hadn't been properly buried, being controlled by the Golden Snake Gang using special techniques.
Therefore, Xu Ziyi and Xu Sheng decided to take their father to search for his body so that he could find peace.
It's quite the hellish joke indeed.
There's a certain absurdity to a necromancer holding up your brother's body, swearing to avenge your brother.
Xu Sheng was actually quite satisfied with the outcome, after all, Magistrate Yushao had specifically instructed him upon leaving the Secret Realm that the Government Office had completely cleared him and Xu Ziyi of their crimes. After all, Xu Ziyi may have been useless and talkative, but ultimately he did switch sides during the battle, dealing a heavy blow to the Fox Demon.