Hi,
Other than engineering, there are various course options available after 12th Science (PCM).
* You may opt for B.Sc, Agricultural science, Dairy science, Biochemistry, Biotechnology etc.
* You may even opt for BBA, BBM, BCA, B.Com, B.A. LLB, Company Secretary (CS), Chartered Accountant (CA).
* You can also opt for courses outside the stream such as :
-Hotel management
-Fashion design
-Interior design
-Aircraft Maintenance Engineering
-Computer courses
-Animation
-Graphic design
-Web design
-Game design
-Mass Communication
However, other than Science stream you may even explore the opportunities Commerce and Humanities offer.
Thank you :)

Go for army. Or marine engineering also for navy.
And if he/she want to study pursue master in physics/chemistry/maths. And try to clear govt teaching jobs.  

All the best for your future