As soon as a person expires all his deeds come to an end except for the following three:-
1. Sadqa-Jariah, i.e. a deed that continues on (for example, financing the opening for a medical clinic for the poor, building a mosque, school, etc.)
2. Leaving behind such knowledge which will benefit people after one’s death (for example, teaching and imparting knowledge, writing a good book which others may continue benefiting from, a useful scientific invention, etc.)
3. Pious offspring who prays for the deceased.The best thing the bereaved person can do for the departed soul is to pray sincerely for his forgiveness.
Another way of sending rewards to the deceased person is to do those things, which aid in fulfilling the pending obligations of the deceased, for example:
1. By paying off a loan on his behalf, by giving the kaffarah for missed fasts
2. Fulfilling a lawful nazar (vow) made by the deceased person in his lifetime. An example of this could be an intention on the part of the deceased to perform the obligatory Hajj, but for one reason or another he was unable to do so.
3. If any relative gives something in charity or offers a sacrifice on behalf of the deceased, it will be a source of reward for both.
4, By making members of his household, followers of the Quran and Sunnah. This way the deceased will be ensured constant rewards.
Allah knows best.