A and B are children of D.
From (1), C is the brother B and son of E.
Since, the sex of D and E are not known. Hence (1) is not sufficient to answer the question.
From (2). F is the mother of B. Hence, F is also the mother of A. Hence D is the father of A.
Thus, (2) is sufficient to answer the question.
Given: D is the brother of B.
From statement 1, we can detect that D is son of C (son of D is the grandson of C).
From statement 2, we can detect that B is 'Female' (sister of D).
Therefore, B is daughter of C.