Pointing towards Aneesh, a woman said, "His mother is the only daughter of my mother." How is the woman related to Aneesh?

Let's break down the relation step-by-step from the woman's statement:
1. "The only daughter of my mother" $⟹$ Since the speaker herself is a woman, her mother's only daughter must be the woman herself.
2. Substituting this back into the statement: "His (Aneesh's) mother is myself."

Hence, the woman is Aneesh's Mother.