It is a simple question of NSO Class 6 Set A. It means that the lady to whom Abhinav is pointing is his father's sister or Abhinav's aunt. The mother of Abhinav's father or Abhinav's aunt is his grandmother.
Anviksha Vipassana answered this
Answer is grandmother because his fathers mother is grand mother so if he has any brother or sister theywill have the same mother.