I recommend that patients get impermeable mattress covers for all beds and that they get a professional exterminator. To determine the location of the bedbugs, they may need to bring a dog. I also recommend looking for bedbug hiding places, which are usually within 2 meters of where people sleep.
Do it yourself exterminating supplies are not effective against bedbugs, as they don't penetrate deep enough into mattresses or wallpaper cracks or baseboards.
I don't recommend any particular chemical, so I have no affiliation to any treatment options. I am impartial.