I am a coffee drinker, but many, many Americans are not. You might luck out and your guests aren't.
I am a coffee drinker, but I would not drink instant! It tastes like burnt artificial coffee to me (and yes, I've tried some of the newer ones and the traditional instant, too). I would also be 100 percent understanding if my host didn't have a coffee maker, and I'd either go without or go to the Starbucks. Particularly if my host was a stranger! (And I would appreciate the effort gone to by a host who bought instant -- I just don't think I'd drink it even to be nice.)
I am a coffee drinker, and I like tea. Your guests might, too!