The commonality among Madam Bhikaji Cama, M. Barkatulla, V.V.S. Iyer, and M.N. Roy is that all of them were among the prominent revolutionaries outside India operating in different countries during the Freedom Movement.

Madam Bhikaji Cama was a prominent figure in the Indian independence movement and actively worked for India`s freedom from British rule. She lived in exile in various countries, including France and England, and played a significant role in spreading awareness about India`s struggle for independence on international platforms.

M. Barkatulla was also a revolutionary who operated outside India during the freedom movement. He was associated with the Ghadar Party, a revolutionary organization formed by Indian expatriates in the United States with the aim of overthrowing British rule in India. He was involved in anti-British activities and played a role in organizing the Ghadar Mutiny in 1915.

V.V.S. Iyer was a revolutionary who operated from abroad and was associated with organizations like the Berlin Committee and the Indian Independence Committee. He worked towards mobilizing international support for India`s independence struggle and played a role in highlighting the Indian cause in Europe.

M.N. Roy, also known as Manabendra Nath Roy, was a revolutionary and one of the founding members of the Communist Party of India. He was involved in various revolutionary activities and was active both within India and abroad. He played a significant role in the international communist movement.

Therefore, the commonality among Madam Bhikaji Cama, M. Barkatulla, V.V.S. Iyer, and M.N. Roy is that all of them were prominent revolutionaries operating outside India during the Freedom Movement.