Nawab Wajid Ali Shah, the last ruler of Awadh, was deposed by the British in 1856. His deposition marked the formal annexation of Awadh (also called Oudh) by the British East India Company. The British had long been critical of Wajid Ali Shah's rule, accusing him of mismanagement and extravagance, and they used these reasons to justify his removal.
The annexation of Awadh was one of the key events leading up to the Revolt of 1857. The loss of their kingdom and the deposition of their ruler angered many people in Awadh, particularly the sepoys, who had strong ties to the Nawab's administration. This discontent was one of the major contributing factors to the broader rebellion.
Therefore, the correct year is 1856.