。
His father passed away from illness last night.
Literal
Last-night his father [subject-が] illness-[cause-で] pass-away-[past-った].
亡くなる ('to pass away') is the polite/sensitive way to say 'to die.' Using 死ぬ directly is considered blunt or cold in most social contexts — this is a cultural norm worth internalizing. The で here marks cause ('from/due to illness'). お父さん with the honorific お- prefix respects the listener's family member even in narration.