Are we sinful if we subject our father to legal accountability or boycott him after he caused our mother's death, and how should our relationship with him be to please Allah?

We ask Allah to console you in your bereavement for your mother and to forgive her.

You must honor your father and treat him well. What has occurred on his part does not negate your duty to honor him.

It does not appear that you are sinful for questioning your father about your mother's death. However, whoever mistreats or harms him commits a sin.

The ruling on the inheritance of a killer from the slain person varies depending on the type of killing. The determination of this is referred to the court.

No one has the right to prevent an heir from their rightful share.