Father's wife ? Mother;  Mother's daughter ? Sister;  Sister's younger brother ? My younger brother. 

So, the boy is Deepak's brother. 

Only daughter of Kamal's mother ? Kamel's sister. So, Ravi's mother is Kamel's sister or Kamal is the brother of Ravi's mother

i.e., Ravi's maternal uncle. 

The relations may be analysed as follows :

Mother's husband ---> father,  father's father-in-law --->grandfather,  grandfather's son ---> uncle; uncle's daughter ---> cousin.

Jagat is the brother of Priya and Priya is the daughter of Sachin. So. Jagat is the son of Sachin. Now, Rajan is the brother of Sachin. 

Thus, Rajan is the uncle of Jagat 

Q, the Doctor, is the father of T. S, the Housewife, is the grandmother of T and hence the mother of Q. Since there are only two married couples one being that of Q, the grandfather of R. i.e, U must be married to S. Thus, R and T will be both children of Q and these must be the students So, P, who remains, shall be the wife of Q and she alone can be the nurse. Thus, U must be the contractor 

P is the nurse. 

Ankit's daughter's mother---Ankit's wife; Ankit's wife's father---Ankit's father-in-law;
Father-in-law's daughter--- Ankit's sister-in-law. So, Sanvi is sister-in-law of Ankit.

Man's son's sister---Man's daughter.
So, the man's daughter is the mother of the woman's husband. Thus, the woman's husband is the grandson of the man in the photograph.