What is the meaning of 'the Sun and the Moon' in Joseph's dream? And he dreamed yet another dream, and told it to his brethren, and
  said, Behold, I have dreamed yet a dream: and, behold, the sun and the
  moon and eleven stars made obeisance to me. And he told it to his
  father, and to his brethren; and his father rebuked him, and said unto
  him, What is this dream that thou hast dreamed? Shall I and thy mother
  and thy brethren indeed come to bow down ourselves to thee to the
  earth? - Genesis 37:9-10


If we continue to read the book we will see that Joseph's ten brothers bowed before him. Benjamin is a question mark for me, because the Bible doesn't say specifically whether Benjamin bowed or not. But we know that Joseph's father and mother didn't bow before Joseph, because later we read:


  And Joseph made ready his chariot, and went up to meet Israel his
  father, to Goshen; and he presented himself unto him, and fell on his
  neck, and wept on his neck a good while. - Genesis 46:29


So Joseph's father didn't bow before Joseph, and his mother - Rakhel - wasn't alive anymore. The question is, when is the dream fulfilled, and what are the sun and moon?
The Sun and the Moon do definitely represent his father and mother:


  Genesis 37:10 NKJV  So he told it to his father and his brothers; and his father rebuked him and said to him, "What is this dream that you have dreamed? Shall your mother and I and your brothers indeed come to bow down to the earth before you?"


The bowing down does not refer to the physical act of bowing; what it refers to is his having a position superior to them.

Which actually happened and not only did he hold a superior position, but he became their provider and benefactor. And even though he had much power over their lives he still acquiesced to his father with his sons.


  Genesis 48:11through 14 NKJV  And Israel said to Joseph, "I had not thought to see your face; but in fact, God has also shown me your offspring!" 12  So Joseph brought them from beside his knees, and he bowed down with his face to the earth. 13  And Joseph took them both, Ephraim with his right hand toward Israel's left hand, and Manasseh with his left hand toward Israel's right hand, and brought them near him. 14  Then Israel stretched out his right hand and laid it on Ephraim's head, who was the younger, and his left hand on Manasseh's head, guiding his hands knowingly, for Manasseh was the firstborn.


and


  Genesis 48:17 through 19 NKJV  Now when Joseph saw that his father laid his right hand on the head of Ephraim, it displeased him; so he took hold of his father's hand to remove it from Ephraim's head to Manasseh's head. 18  And Joseph said to his father, "Not so, my father, for this one is the firstborn; put your right hand on his head." 19  But his father refused and said, "I know, my son, I know. He also shall become a people, and he also shall be great; but truly his younger brother shall be greater than he, and his descendants shall become a multitude of nations. 


Even though Joseph's dream was predictive of events to come, it in no way degraded the positions of Joseph's parents. It was not God's intent to change the family hierarchy, but to save the Hebrew Nation for his future purposes.

Hope this helps.