Their own deeds have ended, but the Prophet ﷺ said that when a person dies his deeds cease except three: ongoing charity, knowledge benefited from, or a righteous child who supplicates for him. So the greatest gift is duʿā' for them, and Allah taught us the words: "My Lord, have mercy upon them as they brought me up when I was small." Charity given on their behalf reaches them — a man asked the Prophet ﷺ about giving charity for his suddenly deceased mother and he said "Yes" — and so does paying their debts, fulfilling their vows, keeping ties with their relatives and honouring their friends. Note that the scholars differ over whether recited Qur'ān is conveyed to the dead; duʿā' and ṣadaqah are agreed upon and are what the Sunnah directs us to.
Q&A · Family
What can I still do for my parents after they have died?
Evidence — the daleel
On deen2u
Informational, not a personal fatwa. Consult a qualified scholar for rulings on your situation.