which is a better option ? metullurgy in pec or civil in thapar or any stream like ece ormech. in any other college..........or should i prefer any stream in nits........

Hi

PEC  is  a much more recognised college than thapar, Now if u are concerned about the scope of metallurgy in India , then also its fine. You have a lot of options and can generally specialize even during undergraduate coursework. There is really quite a spectrum of jobs for someone with that type of degree. Some different industries are:

Mining or raw material extraction
Raw materials refiners/suppliers (aluminum/steel/etc)
Aerospace
Oil companies (generally for failure analysis or corrosion)
Manufacturing (forging, casting, other materials fabrication of metals, plastics, ceramics)
Thin films, optical coatings, etc
Consulting/research
Laboratory services

If you want to go on to work on an MS or PhD, there's a broad range of things you can study as well:
Alloys
Failure analysis
Ceramics
Corrosion
Welding
Thin films
Mechanical metallurgy
Plastics

Otherwise if u are stilll unsure about metallurgy then go for civil engg. coz its an old branch too, and has also got a good scope with infrastructure development taking place in india at such a good pace. Thapar institute is also reputed but PEC is preferred before that.