In min ummi al-Ḥuwayrith, min is a preposition, umm is genitive and the first term of an iḍāfah, and al-Ḥuwayrith completes the construct. Umm al-Rabāb is likewise a construct phrase.
Wa-jāratihā is coordinated with the preceding reference and carries a third-person feminine pronoun. Umm al-Rabāb further identifies the neighbor, by apposition or explanatory substitution.
Omitting jāratihā from the translation would lose the relationship between the women; treating Maʾsal as a person's name would misidentify the locality.