[doxinwasido]

This is not correct. The souls of certain people are allowed to leave their graves. One example is the prophets. So it is possible when you see someone in a dream, that you have met their soul, but it is also possible that the dream may simply be a creation of your mind.

Graves are places but Barzakh is not a place. it is kind of another world running parallel to this world. Souls of common people cannot leave that world to communicate with others. If you see any common person in dream, it is by no means true that you met his/her soul. jazazkallah