Reference: Fataawa Noor ‘alad-Darb – Question No.6450, Page 277, Volume 12
Question: Other than supplicating, which [other righteous] deeds can I do to honour my father after his death?
Response: [You can give] charity and seek forgiveness [on his behalf], as well as maintain ties of kinship, and honour his friends – you can do all of these [intending by doing so] to honour your father after his death. However, supplicating and seeking forgiveness for him is the best thing [you can do on his behalf].
So I advise you my Muslim brother to supplicate for your deceased, and render your righteous deeds for yourself, because you are in need of righteous deeds [yourself]; and there will come a day when you will wish you had [just] one extra righteous deed [recorded] in your book of good deeds.