As you want to get the details of eligibility criteria to start dispensary/maternity ward after M.Sc Nursing (Gynecology) so here is the information of the same for you:

It's not uncommon to start a dispensary/nursing home by a diploma holder in Homeopathy, Ayurveda and the like.

But, you have to look into the ethical aspects of conducting a clinic/dispensary. Of course, in the rural area, you can manage if nothing becomes abnormal.

You are absolutely eligible to work with a Professional Doctor (MBBS)/ assist him in all his work.

But looking into legal issues I am afraid you cannot run a dispensary on your own name of registration.