Hey raman
you would need to provide them with the documentation thats why they have called you for an interview otherwise they could have called you up to know/ask about the funds.
I am assuming you got all the FD money from your relatives in the form of cash..was it ? or you were given a cheque and you deposited in the a/c ? if it was a cheque and the money provider is a close relative of yours then you can always try and get a letter from him/her stating they would like to see you better qualified and want to help financially being your ______________ (whatever your relation is),, it still doesnt make much of a difference but better than nothing.
P.S - only do it if you got the money through cheque given by ur relative (though you can prove cash payment but it aint easy) and that relative must be somewhat close in relation.
All the best buddy