Learned Mr. Sudhir Kumar has given valuable advice. Kindly follow it.
RD a/c is five year recurring and can be extended.
You have posted that "My elder brother was having an RD account in Post office (Mumbai) from 7 to 8 years."
"I asked post office staff about my brothers account details but they told me we can’t give u any details about his account because it is already closed account between Nov to Dec 2008".
If the instilments are not paid then these can be deposited with late fee upto 6 months and after 6 months a/c becomes inoperative.
Usually the PO agent who has helped to open the a/c or any other senior agent can help to find out the details. This shall be the quickest and easiest way out.
You can also lodge a complaint as per facts to Sub/Post master of the PO or Head Post master of the area or Post master general of the city.
Section 8 of the Hindu Succession Act 1956 takes care of succession of properties of a male Hindu dying intestate (i.e. without executing any will). The said section creates a classification between the different types of legal heirs. Class I legal heirs are the near and dear ones of a person like widow, son mother daughter etc, whereas Class II consists of remoter heirs like brothers and sisters. If there are any legal heirs in class I then the property is divided equally amongst them all and the heirs in class II are excluded.
The nomination indicates the hand which is authorized to receive the amount on the
payment of which the dept. gets a valid discharge of its liability.
If your brother was married and spouse was the nominee she might have obtained the proceeds.
If your brother was unmarried then your mother could have staked the claim being class 1 legal heir.
If neither spouse nor mother has collects the funds then you have another reason to complain suspecting fraud, as advice by Mr. Sudhir Kumar.