MCA

Both MCA and PGDCA courses have been designed to help students to become software professional. Network Engineers job is more of hardware engineering and services. Therefore, you can chose any between MCA and PGDCA.

It is not feasible and also may not be allowed by the universities.

MCA will be better option. In MCA, you will get more practical knowledge in comparison to M.Sc, as it's based on theory. Now most of the IT firm demands for MCA candidates.

Following are some of top MCA distance universities of India:
1. Sikkim Manipal University.
2. IGNOU.
3. Karnataka State Open University.
4. Osmania University – Hyderabad.
5. University of Pune.

Yes, you can do MCA after B.Sc course. Those students who have done class 12th or graduation with mathematics subject then they are eligible to apply. The admission in MCA course is through the entrance exam, which is conducted at the national and state level every year.
If you have good command on the programming language then you should move on this side otherwise not.

Following are the non software fields with good scope in the future -
1. Network Admin
2. System Admin
3. Database Admin
4. Technical support for a product
Point 4 must be avoided if possible. Rest are good jobs. But its hard to grow if you hate or don't know programming.

LNCT is one of the best private engineering colleges in Bhopal for the same.

Prefer MCA for being safe and learn cloud computing and mobile application development as your interest. Diploma can cause you pain in terms of the Degree asking requirements in India.

JNU does not offer MCA by distance learning. You may evaluate IGNOU for same.