This topic might have a better name.
Joan Calder's mother, as that provides a means of disambiguation if there are any other mothers of Joans in the future.
Talk about it here.
Joan Calder's mother was a woman who lived in London in 1943.
When her daughter Joan Calder brought the First Doctor and Susan home for tea, she seemed uncomfortable with Joan bringing people home, though she said that Joan was a "good lass".
The Doctor realised that Joan and her mother were trapped in 1943, though it was 1963 outside, and that Joan's Grandpa was the source of the trouble. When the house burned down, Joan and her mother burned too and were freed. (PROSE: Ash)