Ask HN: What options are there for long-term web site hosting?

A family friend of mine asked me a question the other day that made me pause. She wants to put a QR Code on a grave stone with a URL link to a web site hosting their family tree information. There is little that is more permanent than a grave stone. How would you implement this with long-term thinking. Use a free site? Find a place willing to allow you to pay for 100 years? Is there a service out there that does this already? I thought I'd hit up the hive-mind.