@Elizabeth2243 Here's what I would write in your situation:
"Regrettably, the farmhouse fell short of Homer & Marge's expectations because its listed amenities do not include WiFi or a kitchen. In hindsight, I wish we had been able to establish a better line of communication to ensure that the home was the best fit for their needs."
You can round that out with anything else worth mentioning - like if they checked in on time, left the home tidy, and followed House Rules, and rate appropriately. These guests could have made things easier for themselves if they'd read your listing properly, but I agree with @Mike-And-Jane0 that you can significantly reduce the odds of this recurring if you write a more thorough listing description acknowledging the lack of some commonly expected amenities, and even more so if you double-check that the guest understands what they're getting before you accept a request. (I wouldn't recommend Instant Book, as a unique home like yours better suits the booker who slows down and pays careful attention).
It's all about managing expectations, and helping guests visualize the experience they'll have. If guests can't live out their farmhouse fantasy of frying up farm-fresh eggs every morning, you can at least get them excited about the meals they might enjoy at the pubs up the road.