In the story by Khuswant Singh, the grandmother dislikes music because it has vulgar connotations for her. To the narrator's grandmother, music is for beggars and harlots: those she considers less cultured and sophisticated in nature.
According to the text, the narrator's grandmother holds very conservative views about education. She is also deeply religious. During the narrator's early school days, she accompanied him to school. This was partly because the school was attached to a temple. While the narrator learned the alphabet and the morning prayers, his grandmother read the scriptures in the temple.
At the end of the school day, the narrator and his grandmother walked home together. The two were good friends at the time because the narrator had yet to progress beyond the grandmother's comfort zone. Once the narrator began learning English and subjects outside his grandmother's expertise, he found her less receptive to his efforts to engage her in conversation.
For her part, the narrator's grandmother felt unneeded because she couldn't relate to her grandson's new spheres of interest. In due time, even the music he was learning in school disturbed her. Neither understood the other's inclinations, and because of this, an emotional chasm soon developed in their relationship.