Linux

No, its not necessary, you can prioritise on the basis of your interest and scope of each certification.

The Linux open source operating system, or Linux OS, is a freely distributable, cross-platform operating system based on Unix that can be installed on PCs, laptops, netbooks, mobile and tablet devices, video game consoles, servers, supercomputers and more.
Basic Features:
1) Portable - Portability means software can works on different types of hardware in same way. Linux kernel and application programs support their installation on any kind of hardware platform.
2) Open Source - Linux source code is freely available and it is community based development project.

Hello Akash,
Linux is a "must-know" for anyone interested to work in IT department. Linux is an operating system and provides sufficient tools which assist in advanced programming. On the other hand, CCNA is a networking course certified by CISCO. This course is recommended for those who wish to make make a career in the networking field in the IT sector. Ideally, I would suggest you to pursue both the courses as both are equally beneficial. Rest is your choice.
I hope this answers your question to your satisfaction. If so, kindly upvote this answer. If you have any further questions, kindly revert.

CMC Limited (A TATA Enterprise), Linux Lab Pune and Shivaji Nagar Pune are the best institutes to pursue Linux in Pune.

Linux device driver courses are part of System Programming PG Diploma courses. Very rarely this course is offered as a separate course. You can learn Linux Device driver fundamentals and programming yourselves as you must be having good C and C++ exposure during MCA.

Do Redhat Certifications from a nice institute around you.

Oh, its a wonder and it's going to be the most important skill for anyone.