What is the scope of aerospace engineering? Will I get a good job if I pursue the same from an average college instead of IIT?

Actually, no, because there is a difference between normal engineering and an engineering through IIT. So, there will be difference in the quality of job also.

Scope of Aerospace Engineering is too good and bright in government or public sector and differences of IIT and private is that IIT provides good and reputed company for the student but average college cannot provide this. So, maybe, you have struggled for good job in this field.