When Jesus' family heard that he was in Capernaum, they decided to travel from Nazareth to Capernaum in order to seize him. The Greek verb to seize
is the same verb used when the soldiers came to arrest Jesus on the night before his crucifixion (Mark 14:44, Mark 14:46). Though we do not know exactly what they wanted to do with Jesus, we can assume that they wanted to bring him back home to Nazareth.
21 And when his family heard it, they went out to seize him, for they were saying, “He is out of his mind.”