In 1930's which party accepted that 'Hindustani' should be the National language of India?

Indian National Congress

The correct answer is Option (2) → Indian National Congress

The Indian National Congress accepted 'Hindustani' as the national language of India in the 1930s for several reasons:

By the 1930s, the Congress had accepted that Hindustani ought to be the national language. Mahatma Gandhi felt that everyone should speak in a language that common people could easily understand. Hindustani – a blend of Hindi and Urdu – was a popular language of a large section of the people of India, and it was a composite language enriched by the interaction of diverse cultures. Over the years it had incorporated words and terms from very many different sources, and was therefore understood by people from various regions. This multi-cultural language, Mahatma Gandhi thought, would be the ideal language of communication between diverse communities: it could unify Hindus and Muslims, and people of the north and the south.