The fact is, it's Tuesday now. All the assumptions about no one home Saturday night, maybe they don't know house burned down and animals died, etc. etc. can be thrown out the window. It is very possible the house burned down because of a space heater accidentally being left on and that could just be a horrible coincidence here, but I don't think so.
I believe missing endangered is the right category to have her and the children in.
In my gut something happened to them Saturday night and the space heater was left on by the perpetrator of the crime to cause the house fire to look accidental.
My questions now: where is the room-mate & where is chad?