Dianne Morwood was a terran hab addict and the wife of Sergeant Morwood, her husband serving in the Confederate Army. Her addiction did the couple no favors in terms of finance, forcing her husband to offer his services to crime lord Fagin. Through the arrangement, Dianne's addiction was kept satisfied.
It is likely that she was killed when the zerg invaded Tarsonis.
Notes
Dianne Morwood is mentioned in the novel StarCraft: Ghost: Nova, written by Keith R. A. DeCandido. It is likely that she is named after the Duane/Morwood estate in Grangecon, Ireland, where DeCandido wrote some of the novel (Morwood providing the surname, Dianne likely being a variation of Duane).
References
DeCandido, Keith R. A. (November 28, 2006). StarCraft: Ghost: Nova. Simon & Schuster (Pocket Star). ISBN 0-7434-7134-2.