"You are not going home."
Translation:Nie idziecie do domu.
In Russian you have домой (domoj) that means precisely "towards home". Is there something similar in Polish?
"panie Frodo" (Vocative of "pan"), as you address him directly.
And if you call him "Mr" in the second part, then you also have to do it in the first part. "Kocham pana, panie Frodo".
"Ty nie idziesz do domy" was marked incorrect. Is there a rule for when to drop the subject pronoun?
It's the last letter ("domy") that got it rejected. Otherwise it's fine.
You drop the subject pronoun in most cases, unless you need to emphasize it or unless the subject changes in the middle of the sentence.