And Moses took his wife and his sons, and set them upon a donkey, and he returned to the land of Egypt: and Moses took the rod of God in his hand.
All Commentaries on Exodus 4:20 Go To Exodus 4
Augustine of Hippo
What was said above, that Moses placed his wife and his children on carts so that he might go with them into Egypt, but afterwards his fatherinlaw Jethro met him with them [in his company], after Moses had led the people out of Egypt, one can ask how both assertions can be true. One should realize that after the killing of Moses or of the child that the angel was going to carry out, his wife returned with the children. For some interpreters thought that the angel threatened them to keep a woman from accompanying Moses and thus forming an obstacle to the ministry that God had imposed on him.