Why does Tita see John's great-grandmother in the room?

One day Tita smells something pleasant coming from a small room in the house that causes her to think about Nacha. Intrigued by the smell, Tita goes to the room where she finds an 80-year-old Indian woman who gives her a cup of tea. Tita continues to visit the woman every day until Dr. Brown takes over the space for his scientific experiments. Tita decides that when she begins speaking she will ask for the name of the mysterious Indian woman. I think she understands Tita and comes to comfort her.