Deduction u/s80d for medical exp.- can daughter in law take?

Section 80D now provides for deduction in respect of medical expenditure for super senior citizens if ne medical insurance policy has been taken. The section says that deduction can be claimed for medical expenditure for parents.

Now, suppose Mr A and Mrs. A are couple. S is mother of Mr A. Mrs A incurres medical exp. of Rs 30000 for S (her mother in law). Can she claim deduction? (I have heard an opinion that deduction cannot be claimed by Mrs A , as S is not parent of Mrs A.)

Please clarify.