Hello Deepak,
Master of Science in Pharmaceutical Science is a full time two year course degree. Eligibility criteria for admission to the course is candidate should have passed in the relevant graduate degree from any recognized university. However, eligibility criteria vary from college to college so, if you want to know the eligibility criteria of any particular University then kindly let me know the college name.
After Diploma in pharmacy, you are not eligible to pursue M.Sc. 
You can pursue graduation after diploma in pharmacy such as Bachelor of Pharmacy.
Good luck!