The woman is Abhijit’s mother.

Quick reasoning

  • “The only daughter of my brother” = Abhijit’s niece.
  • That niece is “her granddaughter” = the woman’s granddaughter.
  • So the woman is the mother of the niece’s father (Abhijit’s brother).
  • The mother of Abhijit’s brother is also Abhijit’s mother.

Therefore, the woman is Abhijit’s mother.

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