I asked my mom for permission to study and live abroad for the next 5 years but she refused. As my intention here is good, to get a better scholarship and a better life, is it a sin then to keep pursuing my dream against my mother's wish?
You must avoid hurting the feelings of your mother. She does not want for you but the best,so, you should consider her wish even if it seems to you now against your wish, but be sure that success can never achieved through hurting the feelings of your parents.
Listen to your mother and keep her respect, and be sure that Allah (SWT) will look after you and grant you success from unexpected sources, and protect you from unseen dangers.
Wassalam.