Haha! This is just really funny I'm sorry. I could only imagine what it's like it sounds crazy. Oh the joys of house hacking. How much longer do they have on their lease? You might have to wait it out until it's up. In my area there are some seriously sketchy neighborhoods, not in a violence kind of way but in a methy kind of way and taking them to court is just a bigger headache than letting the lease run out. I think carpet would work the best if you want to spend that money to pay for it. In lieu of putting in a coin washer/dryer, do your tenants pay for utilities? If they have to pay it might discourage them from washing so much. If that doesn't work then coin would be the best next course of action.
I currently house hack but instead of a long-term tenant I use my extra room as a vacation rental and the clientele are AWESOME. Guests don't stay long, they want good reviews so they'll be nice and quiet and usually leave the space super clean, and you get to meet some cool people. My husband and I couldn't live with someone else long-term I think we'd go crazy.