My Grandfather's will states that he left his property to "My Sons, their Heirs and Assignee's". My father is now alao deceased. My mother is alive. My Father respectfully left everything in his will to my Mother. The question is - Do I have partial ownership of this property from my Grandfathers will? I am the last and only son of my father, Or did my Fathers will over ride my Grandfathers?

It would depend upon which state or country you are in, but in general, the words "My Sons, their Heirs and Assignee's (sic)" is interpreted to mean "my sons". Thus (assuming the grandfather predeceased your father) the grandfather's estate would have gone to your father, and his brother(s). Your father thereafter had the right to leave his share to whomever he pleased, his wife in this case.

You should understand, by the way, that in general wills are not automatic. Your mother would have to have probated your father's will in order to receive her share. Similarly, your grandfather's will would have to have been probated.

My father is now alao deceased.

I'm assuming this to mean that your father died AFTER your grandfather. In that case, your grandfather's will was distributed to his sons. Any portion would only have been distributed to his heirs if your father had predeceased your grandfather.

You still may be entitled to a portion of your grandfather's estate if you were to inherit from your mother. But, in that case it would be your mopther's estate, no longer your grandfather's