Sonu, admission to Master's courses in Tata Institute of Social Sciences occurs through TISSNET. Now, you can apply for TISSNET if you fulfill the conditions required as stipulated by the institution. These conditions are known as eligibility criteria. Now, the eligibility criteria for applying for TISSNET in terms of educational qualification in most cases ie for admission to most courses is that the candidate should be graduate in any stream or discipline or he/she must be appearing in their final graduation paper and have to submit their passing certificate by any date stipulated. As far as you are graduate, you can apply for most cases, however, for some courses like MA (Organisation Development, Change and Leadership), Master of Public Health (Social Epidemiology), M.A. Social Work in (Disability Studies and Action) etc , the requirement is that graduation should be from a certain stream or subject or there should be some job or internship experience for the candidates. For mire information about these eligibility criteria, you can use the link

https://www.google.com/amp/s/university.careers360.com/articles/tissnet-eligibility-criteria/amp

As regards to query about choice of specialization, the choice should be such that should generate interest and entertain you. It totally depends on your interest areas, however, there are some courses or specialization which are quite popular among the student groups and some of them are M.A. in (Human Resources Management and Labour Relations) ,  MBA, Master's of Arts etc. So, the specialization should be such that the student feels comfortable in it and is usually chosen by applicantd in the stream as graduation.