When you're just missing a letter in a word, I've always thought that the easiest way to find out what it is is to try every letter in the alphabet, as they are not so many, after all. Apart from "S", there's no letter that would make the word make sense, when placed in front of the characters "HOES" - then again, I'm not a native English speaker so who knows what obscure meaning a word like "thoes" might have (random example). I have no idea what it could be.