Thurma's mother is a character in the The Power of the Dark Crystal.
Following the beginning of the Great Dim, she and the other Ember Queens send Thurma to the surface world using their flame to sustain her during the journey so she could retrive a part of the Crystal and heal Mithra's Mother Sun.
Later on as most of the Fireling race are petrified, the Ember Queen herself remained as the only one due to the other leaders dying. Thurma, after being briefly weakened (having to be carried by Kensho), is taken to see her mother on the verge of becoming petrified. The Queen then tells her daughter that she must be the new Ember Queen now and passes what remains of her flame to her, repeating Chal's message one last time before fading away into ash.