Although Yu'er's family suffered a tragic event tonight, ambushed and backstabbed, with all the family members in the mansion killed, it shouldn't have reached the point of complete annihilation.
After all, for them to own such a large estate, outsiders would need to risk colluding with demons, taking advantage of the main city defense forces being tied up on the battlefield to plot against them, and conceal their identities, masquerading as thieves and blaming wild beasts, afraid of retaliation. This shows the family's power shouldn't be underestimated. Although they're temporarily in trouble, it's not to the point of the city being besieged by demons, and there's no need to help out.
