|A) Mother||B) Sister|
|C) Mother-in-law||D) none of these|
A is a male and married to B. So, A is the husband and B is the wife. C is the brother of A. D is the son of C. E, who is the sister of D will be the daughter of C. B is the daughter-in-law of F whose husband has died means F is the mother of A.
Clearly, F is the mother of A.