Hello Sandeep, according to the eligibility criteria given below you will eligible to pursue M.Sc. in Physics only if you fulfill the following:
For admission into DU PG 2019
M.Sc physics (with entrance)
Any candidate can apply who is a bachelor of science, or engineering/technology, with Physics at the undergraduate degree level. He/she must obtain six credit points in aggregate or equivalent mathematical physics/mathematics/ engineering mathematics. The candidate must score 55% aggregate at the undergraduate degree level.
OR
They should have cleared B.Sc (Hons) Physics from DU or any other equivalent with 55% aggregate percentage.
M.Sc Physics ( with merit)
The candidate must obtain his degree B.Sc (Hons) Physics from DU or any other equivalent with 60% aggregate marks.

For admission into JNU ( Jawaharlal Nehru University)
You must have a bachelor's degree with Physics as one of the subjects. With a pattern of 10+2+3, and you must secure atleast 55 % aggregate percentage.
OR
Those candidates are also eligible who have done their bachelor's degree in Physics, chemistry and mathematics combined, or in physics Hons or B.Tech in electronics/electrical/Computer or mechanical.

For admission into IITs
You will have to give a Joint Entrance Test (JAM) conducted by IITs every year. JAM 2019 was conducted on February 10, 2019.
For getting admission into M.Sc Physics, a candidate must have Physics for 2 years/ four semesters as a subject and mathematics for at least 1 year i.e. 2 semesters.
Also, the candidates from general/ OBC ( NCL) category must secure 55% aggregate in their bachelor's degree, the criteria for SC/ ST category is 50% aggregate.

For admission into NITs
There is a Centralised Counselling for M.Sc admissions conducted by NITs and CFITs which is called CCMN. Only those students can apply for this counselling who have qualified the Joint Admission Test conducted by IITs. Therefore the application for the same will start from the last week of April 2019. There you will have to fill in your choice of course.

All the best!
I hope this helps.