Treat Mother well; you never know when you will need her help.
In this sentence, the second part of the sentence is clearly referring to needing help from "Mother." Mother is a third person, feminine noun, so the correct possessive pronoun is "her."
940 MCQ for effective preparation of the test of Nouns and Pronouns of English Grammar section.
Read the MCQ statement: Treat Mother well; you never know when you will need her help., keenly and apply the method you have learn through the video lessons for Nouns and Pronouns to give the answer. Record your answer and check its correct answer and video explanation for MCQ No. 104-4383.