Complex sentence: While Mogu was with Chandreshwar Bhootnath Mandali, her mother died, and a legend says that on her deathbed the mother told Mogu that her soul would not rest in peace until Mogu became a famous singer.
Split into simpler sentences: While Mogu was with Chandreshwar Bhootnath Mandali, her mother died. A legend says that on her deathbed the mother told Mogu that her soul would not rest in peace until Mogu became a famous singer.