you have to go to the same office from where your grandmother took her nagarikta. they have records of who they issued the nagarikta to. the only rsason why the photocopy will be useful is to find the registration date so that they can easily find the original record from stack of files. this obv would be a non issue if they were using electronic databases. the bottom line is you have to go to the district from where the nagarikta was originally issued.