Is a person who defended his family's honor and was killed because of it considered a martyr, and was his action correct?

We ask Allah to forgive your brother, have mercy on him, and guide your parents and sisters.

If your sisters commit forbidden acts, their father must correct them. If you and your brother advise your sisters kindly, without overstepping, and your parents become upset because of this and the sisters' false accusations, then there is no blame upon you. A brother disciplining his sister with physical punishment or similar, in the presence of the father, is not permissible without the father's permission, and is limited to verbal disapproval.

An exception to this is directly confronting sins and forbidden acts if they are imminent and cannot be rectified except by hand. This falls under the category of enjoining good and forbidding evil, not disciplinary action.

The hadith (definition): "He who is killed defending his property is a martyr; he who is killed defending his family is a martyr; he who is killed defending his religion is a martyr; and he who is killed defending his blood is a martyr" has no relation to your brother who passed away in a car accident. However, it is hoped that a Muslim who dies in a car accident will be among the martyrs.