If P is the husband of Q and R is the mother of S and Q. How is R related to P?

Vimal is the son of Mikka, and Nina is the daughter of Milan. Milan is the sister of Mikka. Who is Milan to Vimal? 

M is the son of P. Q is the granddaughter of O who is the husband of P. How is M related to O? 

Pointing to a girl in a photograph, Sunita said, "She is the mother of Renu, whose father is my son". How is she(Sunita) related to that girl?

Pointing to a man, a man said to a woman, "Your father's only daughter is his mother." How is the woman related to that person.

X and Y are brothers. R is the father of Y. S is the brother of T and maternal uncle of X. What is the T to R? 

Introducing A man, a woman said. He is the only son of my mother ' s mother. How is the woman related to the man?

Directions: Read the following information and answer the questions given below it:
A is the father of C. But C is not his son.
E is the daughter of C. F is the spouse of A.
B is the brother of C. D is the son of B.
G is the spouse of B. H is the father of G. 

Who is the grandmother of D?