The question asks about a financial institution with a crucial role in implementing and financing housing programs in India.
(a) Reserve Bank of India (RBI): RBI is India's central bank. Its primary roles include monetary policy, regulation of banks and financial systems, managing foreign exchange reserves, and issuing currency. While it influences housing finance through its policies for banks and interest rates, it doesn't directly implement or finance housing programs for individuals/developers in the way a specialized housing finance institution does.
(b) Industrial Development Bank of India (IDBI): IDBI Bank (now IDBI Bank Ltd.) was originally established as a development financial institution for industry. It provides banking and financial services. While it may provide project finance that includes housing components for industrial townships, its primary focus is not national housing programs.
(c) State Bank of India (SBI): SBI is India's largest public sector commercial bank. It is a major provider of home loans to individuals and finance to real estate developers. It plays a significant role in the housing finance market by implementing various government-backed schemes, but it's one among many commercial banks doing so. It is not the apex institution for housing finance regulation or policy.
(d) National Housing Bank (NHB): The National Housing Bank was established in 1988 as an apex level financial institution for housing. Its primary objectives include:
Promoting and regulating housing finance institutions (HFCs).
Providing refinance to HFCs and banks for housing loans.
Promoting housing for lower and middle-income groups.
Supporting the development of a sound housing finance system.
Implementing specific government housing schemes and policies.
NHB plays a crucial nodal role in the housing finance sector, supporting the implementation and financing of housing programs in India. It operates under the jurisdiction of the Ministry of Finance, Government of India (earlier, it was a wholly-owned subsidiary of RBI, but RBI divested its stake).
Therefore, the National Housing Bank (NHB) is the financial institution specifically set up to play a crucial role in promoting, regulating, and financing housing programs and the housing finance system in India.
\[ \boxed{\text{National Housing Bank (NHB)}} \]