The best thing you can do for your dear father is to strive to be saalihah and make dua for him. Rasulullah (Sallalahu Alayhi Wasallam ) said when a person dies, all his actions terminate except three:
1) Sadaqah Jariyya (recurring charity)
2) knowledge through which others benefit
3) a pious child who makes Dua for his/her parents.
May Allah forgive you, your father, me, my parents, and all the believers…aameen