Is one who found a copy of the Qur’an and prayer beads in his car during Hajj, and did not know their owner, sinful for taking them to his country, and what should he do?

If only you ride the car, then the Mus'haf (copy of the Qur'an) and the Misbaha (prayer beads) are a gift to you. However, if others also ride the car, then they are a Luqata (found item) and must be announced for a full year in the place where their owner is presumed to be. If their owner is not found, then they become your property, with the guarantee of their value to their owner if he appears, or they should be handed over to the Luqata preservation committee.