Is it compulsory to submit PAN CARD with 15 H for Senior Citizen above 75 whose only income is Pension?

My grandmother who gets Pension and has some Fixed Deposits in Post Office has a joint account in ICICI Bank with me her granddaughter. I deposit money in the Bank and recently we have got some FD's done. The Bank has asked us to submit Pan Card with 15H, but my grandmother doesn't have one? Will getting a Pan Card would effect there pension in any form?