Corrected: Ranjan is one of the best student (students) in my class, but he lacks of confidance (confidence). He is one in (of) those, who help (helps) me completing (complete) the home work (homework) well in time. Thats (That’s) why, he is my the best friend too.

Corrected: Traffic in such a cities have (has) become problem now a days (nowadays). I often see young motorcyclists to ride (riding) at break neck (breakneck or break-neck) speed to show of (off) there (their) superiority over other (others).