Hi, so basically in terms of placements definitely AI and ML. Reason being they are more established in market then network security and IOT in Indian subcontinent. Although, network security or cyber security and AI and ML is very high in hierarchy.

Network or cyber security is going to be a very big field in coming years. For now you could find difficulty in getting job as a cyber security professional but if you find one there is a good chance you are going to get good package. Since, there are less job opportunities for now but the ones that are offers great packages. And you shouldn't underestimate cyber security for now, I am pretty sure cyber security is going to be at its highest peak is coming years.

Same is with AI and ML, although alot of companies have started working on AI and ML so there is a good chance of getting a good package and more job opportunity in it.

So if you have a slight interest in hacking, securing network etc you can opt for cyber security.

If you want to work on machines that mimics human intelligence you can opt for AI and ML.

Hope this is helpful.