Hello Aspirant,

The admission process for this course will vary from college to college , hence you should visit the official website of the college you wish to join in order  to know the exact process. Some colleges may admit candidate based on merit and some may conduct an entrance test. The eligibility for this course would be an MSc degree in social work,psychology or any other mental health related specialization or nursing or medical degrees such as MBBS , BAMS, Unani etc

The link will show colleges that offer the course:

https://medicine.careers360.com/colleges/list-of-diploma-in-psychiatric-and-mental-health-nursing-colleges-in-india

All the best