Who is the "lender of the last resort" in India?

Banks are required to maintain a portion of their demand and time liabilities as cash reserves with the Reserve Bank.

• For this purpose, they need to maintain a current account with the Reserve Bank.
• The current account of the banks is opened by the Banking Departments of the Reserve Bank’s Regional offices.
• The Department of Government and Bank Accounts (DGBA) issues general guidelines for opening the current accounts.

Important Points 

As a Banker to Banks, the Reserve Bank also acts as the ‘lender of the last resort'.

• It can come to the rescue of a bank that is solvent but faces temporary liquidity problems by supplying it with much-needed liquidity when no one else is willing to extend credit to that bank.
• The Reserve Bank extends this facility to protect the interest of the depositors of the bank and to prevent possible failure of the bank, which in turn may also affect other banks and institutions and can have an adverse impact on financial stability and thus on the economy.

Thus, RBI is the correct answer.