Given the prevalence of encrypted torrents and "private trackers", really, that's kind of a "hard" problem.
A better method, might be to:
1) restrict bandwidth, such that "downloading" such things would be mostly fruitless, and
2) utilize something like OpenDNS, and block various domain-name categories.
#2 can be further restricted via forcing a DNS transparent proxy on them, but there's now DNS-over-HTTPS and other some-such non-sense (well, let's just say, it's existence is a highly-contested topic among networking gurus, on the order of the "systemd wars" on Linux. Some believe that the primary reason for mechanisms like DNS-over-HTTPS is primarily to circumvent DNS control via ISPs, whereas other networking admins believe that they should be able to control the DNS of down-stream clients.)
Or, politely, tell them "NO".
If they qualify, there are ISP options for those with limited budgets. (PCsForPeople, Comcast Internet Essentials, etc.) (Edit: Can work out to under $20/mo for internet.)
Edit: That being said, I let a former resident that was a Vet on my hallway in my last apt., "borrow" my internet. He didn't use it for much. I also use to run an "open hotspot". Which I left running while I went on vacation. When I got back, the router was so bogged down by requests, I couldn't even log into it over the local wired LAN. It hadn't gotten hacked, so much, as some of the newer neighbors decided to use it to download torrents, and it was an older N300 router with like 4MB of RAM or something. I didn't torrent myself, so, well, that was the end of that hotspot. I always meant to install a little mini-server and some DNS and content-filtering, but I
never got around to it, because I never found a way to "do it right". I'm probably on "some list" now, for what my neighbors probably downloaded (I have no idea). But trust me, it wasn't me guys, I only torrent freely-licensed Linux ISOs. Because Copyright law. I don't torrent or stream "Hollywood movies", I buy the DVD if I want something on video. (Call me old-fashioned.)
Edit: I've never watched an episode of GoT, either. I could really care less. I just don't watch much TV at all.