"His house is close to her house."
Translation:بَيْتهُ قَريب مِن بَيْتها.
The 1st "house" should be: "baituhu" because the phrase is the subject of the sentence (in the nominative case).
The 2nd "house" is correct, ie. "baitihaa" because of the مِن that turns it into the genitive case.
Please see my post above, I have written the complete ending diacritics, but note that it is based on Standard (and not Slang).