What is the relation in between third oldest person of the family and Y’s mother-in-law and who is third oldest person of the family? 

Study the following information carefully and answer the questions given below. Six members of the family namely A, F, Y, D, Z and S live in eight different floors of building. Two of the floors in the building are vacant. The lowermost floor of the building is numbered one, the one above that is numbered two, and so on till the topmost floor is numbered eight. Each one of them works in different banks, namely HDFC, SBI, BOI, PNB, UCO and ICICI (but not necessarily in the same order). There are two married couples in the family. A’s son Z lives on an odd numbered floor above the floor numbered four. There are three people live between the two vacant floors. There are only three floors between S’s wife and the one who works in PNB. The one, who works in UCO lives immediately above S. The Person who lives on lowermost floors is younger than the oldest person of the family. There are only three floors between S and D’s grandfather. The one, who works in ICICI lives immediately above the one who works in HDFC. The number of floors above S’s brother is same as the number of floors between D’s father and S’s wife. S’s mother lives immediately above the one who works in BOI. Z is the son of
A. The number of floors between Z and the one who works in SBI is only one. The one, who works in SBI lives immediately below one of the vacant floors. The person lives immediately above the vacant floor is younger than D’s aunt. S is the uncle of
D. The floor number of the vacant floors are even-numbered. Y is the wife of S. Only two floors are there between the one who works in ICICI and PNB. D’s grand mother lives immediately below one of the vacant floors and does not live on the ground floor. F neither lives on floor number 5 nor floor number 2. The one, who works in SBI, lives on one of the floors below the floor number 4. S is younger than only second oldest person of the family