We know that Jesus had twelve disciples (see Mark 3:16–19 for a list of their names). Where previously only Peter, James, and John accompanied Jesus to the house of Jairus (Mark 5:37), now they all come with him to Nazareth. Presumably, Jesus wants them to meet his family and friends from that town and knowing what will happen when they get there, he also wants them to learn that rejection is a normal part of ministry.
Jesus taking along the disciples also indicated that his visit to his hometown was not merely a private one but more like one of a rabbi with his disciples.1 As Mark 6:2 elaborates he had come to continue his ministry of teaching as he had done at various other areas surrounding the Sea of Galilee.
1 He went away from there and came to his hometown, and his disciples followed him.