The correct answer is: Finance Commission.
The Finance Commission is an independent body constituted by the President of India every five years to review the financial relations between the Union and the States. It makes recommendations on the distribution of net proceeds of taxes between the Union and the States, the principles governing grants-in-aid to the States, and the measures needed to augment the Consolidated Fund of a State.
The NITI Aayog is a policy think tank of the Government of India, established with the goal of accelerating economic growth and sustainable development. It does not have any role in the distribution of grants-in-aid to the States.
The Planning Commission was a body that was responsible for planning the economic development of India. It was abolished in 2014 and replaced by the NITI Aayog.
The Comptroller and Auditor General of India (CAG) is an independent constitutional body that is responsible for auditing the accounts of the Union and the States. It does not have any role in the distribution of grants-in-aid to the States.