Man now I feel like doing the olive oil treatment just to fool my brain into not itching. I wonder if you can use that all over or just hair. I was telling my mom about it and she is downstairs right now itching. I am really sorry you guys are in this position. Dare I hope they have no kids.
If you check those links I posted above there are examples of scabies in there. Very ucky. We have relatives that did foster care and we saw it a few times. Its pretty nasty looking.
Are they sure its bed bugs and not some equally ucky buggy? I would put everyone in disposable clothing and I would toss them any anything else that was there in trashbags. You can spray, put DE, whatever. Maybe in a year or so you can pull the stuff back out. It would not be coming into the...