Deeds that Benefit a Deceased Person after His Death
5-3-2002 | IslamWeb
Question:
My 27-year-old sister died with her 8-year-old son. I can feel her around me. Is that possible and what can I do to help her?
Answer:
All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad 
is His slave and Messenger.
After death, the souls are withdrawn (by Allah's Might) from the bodies to the world of Al-Barzakh (an interval period between worldly life and the Hereafter). Al-Barzakh is a form of life, which only Allah Knows well. He has decreed that no soul will come back to this present life.
Allah Says (what means): {[For such is the state of the disbelievers], until, when death comes to one of them, he says, "My Lord, send me back. That I might do righteousness in that which I left behind." No! It is only a word he is saying; and behind them is a barrier until the Day they are resurrected.} [Quran 23:99-100]
Allah, The Great and Almighty, has also informed us of the fact that He recalls the souls and holds on to anyone for whom death has been decided.
Allah Says (what means): {Allah takes the souls at the time of their death, and those that do not die [He takes] during their sleep. Then He keeps those for which He has decreed death and releases the others for a specified term. Indeed in that are signs for a people who give thought.} [Quran 39:42]
As for helping your dead sister, it is proved that Abu Hurayrah 
narrated that the Prophet said: “Among the actions and good deeds for which a believer will continue to receive reward after his death are knowledge which he taught and spread, a righteous son whom he left behind, or a copy of the Quran which he left as a legacy, or a mosque which he built, or a house which he built for the wayfarer, or a stream which he caused to flow, or a Sadaqah (charity) which he gave from his property when he was alive and in good health. He will continue to receive the reward of these deeds after his death.” [Ibn Maajah, Ibn Khuzaymah, and Al-Bayhaqi]
Al-'Ajlooni said in Kashf al-Khafaa Book: “This Hadeeth includes a good chain of narrators according to At-Tirmithi.”
Scholars of Islam deduced from the above-mentioned Hadeeth that paying Sadaqah on behalf of the dead has a great excellence.
Abu Hurayrah narrated that the Prophet said: “When a man dies, his deeds come to an end, except for three: a continuous charity, knowledge by which people derive benefits, and a pious child who supplicates for him.” [Muslim]
Therefore, the continuous charity is of many kinds, among which are the following:
1) Building a mosque on behalf of a deceased.
2) Donating some wealth for a charitable purpose such as helping students, or for establishing an Islamic Library for the service of knowledge and scholars.
3) Building hospitals.
4) Building orphanages and old age hospitals.
5) Building schools, Quran memorization houses, and a house for rent for the benefit of the poor and needy.
Sadaqa (charity) also includes digging a well and planting a tree on behalf of the deceased.
For more benefit on deeds that benefit a deceased person after his death, please refer to Fatwa 84938.
Allah knows best.