Is this a standalone word that means "home" or is it a different case form of дом, and if so which case is it? Thanks
Russian has two adverbs corresponding to English "home" (used as an adverb):
Домой (direction): Я иду домой = I am going home.
Дома (location, at home): Я дома = I am home.
It means "home," but in a directional sense. It's used for motion towards/location change to home. For example, Я иду домой...I am going home. It's sort of a counterpart to дома (accent on the first syllable), which functions as the locative of дом (ie. At home). These are frozen grammatical forms which come from older Russian declension patterns.
I agree with what everyone said here. Another way you can think about it is "homeward" which, as others have said, implies directionality as opposed to just "home"