Is not accompanying a frequently angry father — who mistreats his family, and whose harm reaches the point of severe beating — to the mosque considered an act of disobedience?

It is not permissible to dislike one's father, abandon him, or mistreat him, whether by word or deed, as Allah Almighty says: "So do not say to them [even] 'uff' and do not repel them but speak to them a noble word." It is permissible to advise him with wisdom and gentleness if he does something inappropriate, while being keen to show him dutifulness even if he mistreats you, for disobedience to parents is one of the greatest major sins. It is obligatory to be keen on performing congregational prayers in the mosque, and it is better to accompany the blind father to the mosque to help him, as this is not considered an excuse for failing to pray.