Arlyne Jorgensen Scott was the mother of Montgomery Scott.

Half-Scottish and half-Danish, she was fair-skinned and blonde. (TOS short story: "Bum Radish: Five Spins on a Turquoise Reindeer")

In 2273, the omnipotent being Weyland sent Montgomery Scott back in time to Scotland in 1746, during the Jacobite rebellion. While traveling across the moors, Scott had a vision of the land personified as a woman, whom he initially mistook for his mother. He reflected on this occasion that he had not heard his mother's voice in a long time. (TOS novel: Home is the Hunter)

It is not specified whether Scott's mother is dead in 2273, or whether he has simply been out of contact with her. Given the recentness of the Enterprise refit in Earth orbit, the former seems more likely.