Who is mother of G ?

A is the mother of B, who is the sister of C, and H has two children B & C, => A is the wife of H and they have two children B & C.

D is the son of C, and D and E are brothers, since F is the mother of E, => C is the husband of F, and they have two sons D & E.

The flow chart will be :

where, (m) represents male

(f) represents female

-- represents married couple

= represents siblings

| represents children

Now, G is the granddaughter of A, which means G is the daughter of A's child and since A has two children

=> G's mother can be either B or F.

Ans - (D)