Annie Jones's grandmother is the grandmother and former legal guardian of Annie Jones, better known as Alex.
For an unknown reason, she became her granddaughter's legal guardian, presumably because the rest of Annie's family was dead. When Annie was eight years old, she was kidnapped by Celia's Family. At some point following Annie's kidnapping, her grandmother died, presumably of natural causes.
Annie, now known as Alex, eventually ended up in Sioux Falls, South Dakota after running away from her vampire family. Local Sheriff Jody Mills was able to identify Alex through a DNA test and learned that her grandmother, her only living relative, was dead. Despite her seemingly uncaring attitude, Alex asked Jody about her grandmother and Jody was forced to admit that she was dead. Alex appeared upset for a moment by the news, but brushed it off, stating that her grandmother had been old when she'd been taken so it was to be expected.
With Alex's grandmother dead and Alex having no other living relatives, Jody adopted the girl herself.