There were only 11 disciples on the mountain. The group was incomplete because one had betrayed Jesus and given in to despair. The others hadn’t acquitted themselves much better during the time of trial. The impetuous one had denied Jesus three times. Some had scattered and hid. Together or on their own, it just didn’t seem they were enough.
So they went back to Galilee. Jerusalem hadn’t turned out as they had expected. Galilee was safe. They could lie low, like a light under a bushel basket. Maybe they could get their old jobs back. Their old lives too.