I am not exactly clear from the question who is who, but if I follow your grandfather had at least 2 daughters (your mom and another). You are making a presumption that your aunt's money should go to your mom but this is not the case.
Your grandfather was free to leave his assets to whomever he wished. The only exception to that is that a surviving spouse cannot be completely cut out of a spouse's estate. Other than that, there is no obligation - parents are free to disinherit children as they please. Absent some other facts you may raise you cannot get around that. I would suggest that if you really want to be sure about your rights, you contact an attorney, especially if there is some type of fraud or coercion involved.
This is not legal advice nor intended to create an attorney-client relationship. The information provided here is informational in nature only. This attorney may not be licensed in the jurisdiction which you have a question about so the answer could be only general in nature. Visit Steve Zelinger's website: http://www.stevenzelinger.com/
Take the will to an attorney to review it. Nine years is a long time to contest a will. If it was accepted to probate, the you may have missed the boat.
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