You say you know he wrote a will...but someone can always destroy or revoke their will. If he had a safe deposit box typically the will would need to be probated to get the safe deposit box open. If the will that was found named an executor you should be able to petition the court to get that executor to open the box and probate the will (the later 2007 will) that is more recent or valid. You need a lawyer.
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.
I agree with Atty. Zellinger that you need an attorney. We don't know what either will says or was supposed to say, but since a child has no right to inherit, be careful what you wish for as the will may disinherit him. If the 2004 will was probated, and it left everything to his spouse, and now spouse has died without a will, her estate will pass to her children in equal shares.
To questioners from West Virginia & New York: Although I am licensed to practice in your state (in WV, on inactive status as of 9/13), I practice on a day-to-day basis in Massachusetts. I answer questions in your state in areas of the law in which I practice, and in which I feel comfortable trying to offer you assistance based on my knowledge of specific statutes in your state and/or general principles applicable in all states. It is always best, however, to work with attorneys and court personnel in your own area to deal with specific problems and factual situations.