Under whom was CP Ilbert a law member of the council?

Correct option is C

The correct answer is: (c) Lord Ripon.
 Sir Courtenay Peregrine Ilbert served as the Law Member of the Viceroy's Council in India from 1882 to 1886. During this period, the Viceroy of India was Lord Ripon.
 Sir Courtenay Peregrine Ilbert drafted the Ilbert bilI which proposed that cases involving British staff in India be presided over by senior Indian magistrates. The bill was fiercely opposed by the owners of British tea and indigo plantations in Bengal.
 Lord Lytton: Lord Lytton served as the Governor-General from 1876 to 1880.
 Lord Cornwallis: Lord Cornwallis was Governor-General from 1786 to 1793.
 Lord Curzon: Lord Curzon served as Viceroy of India from 1899 to 1905.