OMG they are AWFUL!!!! Bedbugs are crafty little critters and they really get around. Tell your friend to GET A PROFESSIONAL EXTERMINATOR. Whatever it costs, it’s worth it. This is not a do it yourself project!
The cleanup is a HUGE pain. Every single item of clothing and linen will have to be laundered in hot water and bagged; every item will have to be removed from every drawer in the affected rooms; the furniture will be turned over so it can be sprayed from all angles; pictures will have to be removed from the walls; etc. – the exterminator will have the details. I would not trust an exterminator who suggests spraying without taking everything out because the bugs hide. Once everything is clean, put the mattresses & box springs in zippered bags.