If you can hit the bugs directly, a lot of common household chemicals will slay them.
It’s the bugs we can’t directly slay that are causing the problems. Most modern insecticides might be a joke to them. They are only looking to eat blood, so they won’t be eating other things that aren’t blood but which might have insecticides on them.
Well I take it a lot of contact poisons doesn’t work on them very well. Like praying spectracide or whatever around a clean bed/sleeping area.
Freegards
If your friend can possibly afford it, call the exterminator asap - they multiply quickly making it that much harder to rid one's home of them.