I have read that there is no importance to Qul/Khatam or Barsi, but people do it. When someone does Qul of a deceased one, what should one recite? I don't know how to read the Quran except for a few Qul's, Ayat-ul-kursi etc. so what else can I do? And if someone visits the deceased grave. What dua should one read? Some people read really long Dua's when next to a grave and I feel guilt for making dua and leaving quickly.
Best Is Surah Mulk as it gives one protection from the punishment of the grave.
One of the companions of the Holy Prophet Hazrat Muhammad (PBUH) has already repaired his tent on a tomb without knowing it. When he came to know the tomb, he recited this Surat al-Mulk. Then he went to the Holy Prophet Hazrat Muhammad (P.B.U.H) and related the incident and his recitation of Surah Mulk. Prophet Hazrat Muhammad (PBUH) said:
“It is the prevention of the punishment of the grave”.
If you want give him its reward you may recite this beneficial Surah.