|A) Mother||B) Sister|
|C) Aunt||D) Sister-in-law|
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.
F is the mother of A and C is the brother of A. So, F is the mother C.