The 'diwani' of Bengal was transferred to the East India Company in which year?

1765

The correct answer is Option (3) → 1765

The diwani of Bengal transferred to the East India Company in 1765.

In 1765, following the Treaty of Allahabad, the Mughal Emperor Shah Alam II granted the East India Company the diwani rights — the authority to collect revenue — for Bengal, Bihar, and Orissa. This marked a major step in the Company's transformation from a trading body to a territorial power in India.