Is there a sin upon one whose brother shunned her for days without cause, merely because she asked him to remember Allah out of fear of the evil eye?

What you mentioned about your brother's bad manners and his abandonment of Muslims is forbidden, and it is more severe if it is between blood relatives. Greater than that is his disobedience to his mother, for it is one of the gravest major sins.

As for your stance, as long as you do not sever ties with him, there is no sin upon you. However, it is better for you to initiate conversation with him, unless there is a legitimate Sharia benefit in avoiding communication with him to change his condition. The best of those who dispute is the one who initiates the greeting of peace.

We emphasize that forgiving the wrongdoer increases a Muslim in honor and dignity, and it is a means to attain Allah's forgiveness and pardon.