Is it a good option to study Economics (Honours) in Loreto College Kolkata?

Yes. Loreto is one of the best colleges in Kolkata. It is famous for its English and Humanities department. 

Calcutta University is among the few universities in India that offers a B.Sc. degree in Economics, so it is suggested that you go for a B.Sc. Honours degree rather than a BA degree.

Loreto College is a reputed institution, if to get an opportunity to pursue Economics there you should definitely go for it.

You should also keep in mind that it is a very strict and disciplined institution. Here you must maintain 80% attendance. If you want to study in a more lenient environment opt for other colleges instead.