In the primary universe, Mickey Smith's grandmother died when she broke her neck after tripping on the stair carpet Mickey forgot to fix. However, on a parallel Earth, he discovered her to still be alive.
Rita-Anne had a tense relationship with her grandson, as she did not approve of his running off with the Preachers. (TV: Rise of the Cybermen) In 2007, when the Cybermen began to summon the humans for upgrades through their ear pods, she was one of those summoned, but she was not upgraded. The death of Ricky Smith left her with no one to take care of her, which was a major deciding factor in Mickey deciding to stay on the parallel Earth. (TV: The Age of Steel)
Rita-Anne came to live in the Tylers' mansion, where she eventually passed away peacefully. Just as her survival helped Mickey decide to stay on the parallel world, her death ultimately inspired him to return to his original Earth when the opportunity arose. (TV: Journey's End)