At that time in history the Jews believed that the soul of the dead hovered over the grave for several days after they died. One reason Jesus wanted to meet the diciples there was so there would be no question that the post resurrection apperance was real and he was not a ghost.
This was also a call to faith ( Mark 8:31, 9:31, 10:34, Luke 9:22). For the disciples to go there to meet Jesus would be an act of faith. They would have to believe the eye witness account of the women who saw Jesus alive from the dead. They would also have to believe that Jesus would be there. This would also separate them from the highly emotional enviroment in Jerusalem.
This location would easily allow Jesus to choose the witnesses of His resurrection. The passover pilgrims would be going home and a remote mountain in Galilee would be a good place to go and meet alone with His disciples.
Galilee was home. Jesus knew the psychological effect on the disciples. Most likely they were in despair, broken and confused, Judas was dead and Thomas was deeply depressed. His goal here was to regroup these men and reconstruct their faith. When a younger person makes a mess of their lives most often they go back home where they are secure and have good memories. Jesus knew that taking the disciples back to Galilee would remind them of their good times with Jesus. This would also get them out of the hostile enviroment of Jerusalem a place of conflict and a place of death and attacks by the Jeish leadership. In Galilee it would be easier for them to see their mission of world evangelism.
Galilee served every purpose that Jerusalem did not. The Lord knew best then as He doe`s now. We all need to trust the Lord and we need to believe He knows what He is doing.