M.A

The eligibility criteria of M.A. in Percussion of is given below.
Eligibility criteria : Honours graduate/ Post Graduate with Honours from any U.G.C. recognized University in any subject or its equivalent having special aptitude in the concerned subject are eligible to apply.
Admission to the courses under the Faculty of Fine Arts will be made through Admission Test. Marks obtained in the Admission Test will be counted towards preparation of merit list.
Reservation of seats for the reserved categories of ST/SC/OBC/PH will be as per the West Bengal Higher Educational Institutions (Reservation in Admission) Rules, 2013. Reserved category candidates from the state other than West Bengal will be treated as unreserved category.
So from above simple graduate students are not eligible for the asked course because course required the Hons. degree or PG.

The eligibility criteria of M.A. in Economics (Specialization in World Economy) of JNU is given below.
Eligibility criteria :
(i) Bachelors degree (with 50% marks in aggregate) in the following subjects: Economics (Hons.) with
Mathematics as a subsidiary subject; or Mathematics (Hons.) with Economics as a subsidiary subject; or
Statistics (Hons.) with Economics and Mathematics as subsidiary subjects.
(ii) Any other Bachelors degree (with 60% marks in aggregate) with courses in Microeconomics,
Macroeconomics, Mathematical Economics and Statistics.
So from above Bachelor degree in Economics (Hons.) with Mathematics as a subsidiary subject is needed for M.A. in Economics (Specialization in World Economy), hence you are not eligible for the asked course.