Granny McCrimmon
Granny McCrimmon was the grandmother of Heather. She lived in a tiny village called Stillmuir. (COMIC: A Merry Little Christmas) Heather had a good relationship with her and often vistited her. Even during Heather's travels with the Tenth Doctor, Heather never forgot her granny.
In December 1965, Heather travelled with the Doctor to the Norwegian wood to get a Christmas tree for her granny. After they got a beautiful tree the Tenth Doctor and Heather were going to Granny McCrimmon's house together. (COMIC: The Goats of Christmas Past)
At Granny's house, Heather's family was celebrating Christmas when the village vanished and was taken away by Selby and Kerlow. They intended to capture and study the humans' celebration. The Doctor, however, had a better idea and invited the aliens to experience Christmas by returning the village and staying at Granny McCrimmon's, who fortunately was a bit short sighted and assumed the blue aliens were just cold friends. (COMIC: A Merry Little Christmas)
Behind the scenes
Granny McCrimmon's name was given to her in the comic story The Goats of Christmas Past. Granny's first name wasn't mentioned.