Even though the guarantor died while the loan is still outstanding and the borrower is living, it is for the borrower to repay the loan amount, the bank may not have any right to recover the loan amount from a dead person's account.
However since the amount has been given as collateral security, in the even of the borrower defaulting the loan payment, the bank may discreetly avail that collateral security from the deceased guarantor's account.
However you may issue a legal notice to release the amount and then drag the bank to consumer forum seeking to redress the grievances.