"You come from home."
Translation:Tu domo venis.
Nouns that use the locative (cities, towns, small islands [usually only have one city or town on them], and a few other nouns like domus) will drop the preposition.
Nouns that do not use the locative (like urbs) will not (or at least not normally if there are any weird cases I am forgetting).
If we are talking about a physical movement 'to home' we would use domum, works as though there is an ad in front (like ad urbem -> "to the/a city"). Tu domum venis -> "You come home."
If you are trying to differentiate between the ablative and the dative, that will likely depend on context, what verb is being used, etc. I don't see how you could use the dative here but maybe someone else would know.