Sam and the team finished off the Night Demon family. Except for the guy named Davon, the rest of the core members were killed. Davon was throw into the chessboard instead as an insurance plan.
Usually, Sam wouldn't have gone for this unnecessary bloodshed, this time he made the decision, because the Night Demons are formidable foes, for him to just let them be and stay with peace while they are still breathing under his neck.
As for Davon, the outer Deacon of the Five Great sects being his father, he wanted to use him as a hostage if the situation arises where the father manages to catch up with them.
After getting ahold of the family heirloom, Sam went into the underground temple where the whole of the Night Demon family was gathered. Most of them are weak and would take decades before they could become qualified to even think of making trouble for Sam. He let them live, but not without any other plan.
