It appears that Husband's Will has already been probated (well over 5 years ago), so that shouldn't be an issue anymore.
So, assuming that the Will that Wife executed in 1998 was valid, then it should be the will that is probated because it is her last will.
I'm not sure I understand why you provided quite as much detail as you did. The husband died in 1998 and his wife served as executor; his testamentary scheme was to leave her "half of his land and his home." I'm not sure if you are suggesting that the entire home or just half of it. I am similarly not sure whether the "land" you refer to the land on which the "home" stands or whether you are referring to multiple parcels of real property, at least one of which had a home on it.
Thereafter, the wife changed her will. You indicate that during her lifetime, the wife signed over the deed to the house to her son. By this, I suspect you mean that she named him as a joint tenant with right of survivorship, rather than an outright conveyance. That being the case, it would appear that the son became entitled to the house upon his mother's death, unless half of the interest in the home remained in trust.
Good luck to you.
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