Hello,
If you have completed a bachelor degree in psychology, then you are generally eligible to apply for a post graduation diploma in rehabilitation psychology. This course usually requires a background in psychology at the undergraduate level. The final eligibility depends on the rules of the institute of mental health in Ahmedabad, but a bachelor degree in psychology is usually accepted for admission to this diploma. You can apply if your degree is from a recognised university and meets their basic criteria.
Hope this helps you.