What can i give as a thoughtful thank you gift?

Awww, what absolute godsends they sound like!

I would go fancy alcohol or chocolate that would be difficult to get rurally, a hamper of fun and interesting foods etc for them to try, or something for them to use in the home, if they don't often leave because of the work they do. Things like... a cheese board or entertaining platter, or a really beautiful wool throw blanket for the couch.

I think it's a really lovely idea to gift them experience which gives them 'permission' to get away too, assuming they'll actually be able to!

Etsy has some really cool gift boxes that you can personalize for anyone. There are at home spa kits, candy and cookie boxes, even little dinner kits and garden boxes. I have quite a few thank you gifts to buy and I think i'm going to get them all there

If they live on a farm, I would consider giving them something practical that they may be able to use that is quality.

For example:

If they have a brand of boots or outerwear that they use, a generous gift card that they can use may be appreciated.

Cast iron cookware also makes for a classy gift. Lodge has a "cook all" that can be used in the outdoors, as well as some versatile and useful pieces. Le Creuset of Staub are enameled cast iron pieces that can be used on both stove top and oven (but not over a camp fire) that most wouldn't dream of receiving as a gift.

Gifting your time such as a personal spa day with a 90 minute massage is a generous gift rarity.

Just some thoughts.