How can he seek
    the forgiveness of one who has died?
Question

                My grandmother died 4 years ago (me she be
      in Heaven, Amin). I have grown up in front of her and have great memories of her. She
      taught me to pray and said great and wise things, I have tremendous love for her.
      I foolishly did something that I should not have, for which I am really sorry. I may have
      humiliated her in a way, but she didn't say any thing about it. 
      I haven't had a chance to ask her forgiveness, I have repented to my sin. I constantly ask
      Allah to forgive me. Is there a way to ask my grandmother for forgiveness now? I have
      given great thought to it, but I am unable to come up with any suitable solution.
      I would be grateful if you guide me in this matter.
      I ask Allah for forgiveness and guidance for all who are alive and dead.
Praise be to Allah.Since your grandmother has died and gone to her Lord,
    you cannot know whether she has forgiven you or not. There is no way that you can ask for
    her forgiveness now that she has died. This confirms the importance of the hadeeth of the
    Prophet 
 (peace and blessings of Allaah be upon him):
Whoever has wronged his brother with regard to his honour or
    something, let him ask him for forgiveness before the time when there will be neither dinar
    nor dirham, and if he has any good deeds it will be taken from him in proportion to
    the wrong he did, and if he does not have any good deeds (hasanaat), some of the
    other person's evil deeds (sayiaat) will be taken and given to him to
    bear. (Reported by al-Bukhaari, 2296).
    Ibn Hajar (may Allaah have mercy on him) said in his
    commentary on this hadeeth:
 Whoever has wronged his brother  i.e., if he
    has done something wrong to his brother.
with regard to his honour or something  i.e.,
    anything else this includes all kinds of wealth and wounding, even a slap in the
    face and so on. According to a report narrated by al-Tirmidhi, with regard to his
    honour or his wealth.
Before the time when there will be neither dinar nor dirham
     i.e., the Day of Resurrection.
Some of the other person's evil deeds (sayiaat) will
    be taken  i.e., they will be taken from the account of the person who was
    wronged  and given to him to bear  i.e., they will be added to the
    account of the wrongdoer.
Muslim also narrated a hadeeth similar in meaning to this through a
    different isnaad. This version is clearer in meaning: The one who is bankrupt among
    my ummah is the one who will come on the Day of Resurrection with prayer, fasting and
    zakaah to his credit, but he will come having slandered one person and shed the blood of
    another and wrongfully consumed the wealth of a third, so (his victims) will be given some
    of his hasanaat (good deeds), and if his hasanaat run out before the score is settled,
    some of their sins will be taken and thrown onto him, and he will be thrown into
    Hell.
According to a report also narrated by al-Bukhaari from Abu Hurayrah,
    the Messenger of Allaah 
 (peace and blessings of Allaah be upon him) said: Whoever
    has done wrong to his brother, let him seek his forgiveness, because in the Hereafter
    there will be no dinar or dirham, and let him ask for his forgiveness before some of his
    hasanaat are taken and given to his brother, and if he has no hasanaat, some of his
    brothers sayiaat will be taken and thrown onto him. (Reported by
    al-Bukhaari, 6053)
Abu Naeem reported from Ibn Masood that a person will be
    taken by the hand and made to stand before all of mankind, and a caller will cry out:
    This is So and so the son of So and so. Whoever is owed anything by him, let him
    come forward. So they will come forward, and the Lord will say, Give them what
    is due to them. He will say, O Lord, the world is finished, so how can I give
    them anything? He [Allaah] will say to the angels, Take from his righteous
    deeds and give each one what he is asking for. If he is to be saved and there is
    even a mustard-seed worth of his hasanaat left over, Allaah will multiply it until He
    admits him thereby to Paradise.
Ahmad and al-Haakim reported from Jaabir from Abd-Allaah ibn
    Unays, who attributed it to the Prophet 
 (peace and blessings of Allaah be upon him):
    No one of the people of Paradise will be allowed to enter Paradise when one of the
    people of Hell has been wronged by him, until I settle the score, even with regard to a
    slap in the face. We [the Sahaabah] said: O Messenger of Allaah, how will that
    be, when we will be gathered barefoot and naked? He said, By virtue of
    sayiaat and hasanaat. (Fath al-Baari Sharh Saheeh al-Bukhaari).
    In any case, you have taken a very important step, which
    is repenting to Allaah. If you sincerely repent to Him and do as much as you can to honour
    your grandmother (for more details, see Question #763), and she sees in her record (on the Day of Judgement) that you
    sought forgiveness for her, perhaps she will forgive you on that Day if she had not
    already forgiven you in this world. Make lots of duaa for her. May Allaah
    forgive us all.