pls tell me which one is a better option : electronics at guwahati or eng.physics at delhi

Take Engg Physics only if you really love the subject. It has mainly research focus. Electronics is core branch. Also try for BHU Electronics because BHU is consistently ranked higher than Guwahati and IIT tag was the reason for it to close  lower in last few years.

You could also consider Roorkee Mech & BHU Mech but Electronics is more popular branch for many reasons. Don''t go for Delhi option unless you really love that branch.