This woman is the girlfriend of Raj's father V. M. Koothrappali.
She was seen only through a picture on Dr. Koothrappali's phone when Raj called him and asked him to arrange a marriage for Raj since he had had enough of losing his girlfriends.
When his father showed him the picture, he thought that she was the girl he was going to set his son up with, but it turned out that she was who Raj's dad was dating. Dr. Koothrappali then says that she might have an older sister but later on, he sets Raj up with someone else entirely.