She has a strong relationship with Cinderella: Cinderella's mother (Hayley Atwell) has already passed away by the start of Disney's cartoon, but in the live-action film, she's seen in happy, emotional scenes from Cinderella's childhood.
She's at the core of Cinderella's character: The influence and spirit of Cinderella's mother is one of the key threads that weaves the live-action film together. For one thing, it's her mother's advice ("Have courage and be kind") that Cinderella lives by, and for another, it's through singing her mother's song that Cinderella is eventually found by the Prince in the end, leading to her happily ever after.