Is the death of a father, who used to pray all night and recite the Qur’an until dawn, and who was afflicted with calamities that only increased his faith, by falling in the bathroom, considered a bad ending, and will he be resurrected in the state in which he died?

Dying in a bathroom is not an indication of a bad ending (su' al-khatimah). We ask Allah for mercy upon your father, and we advise you to be patient, to think well of him, to ask for mercy upon him, to seek forgiveness and supplicate for him, and to give charity on his behalf or perform Hajj and Umrah (definition) on his behalf if possible.