Are you sure the 1099-NEC is not for his services as executor of the estate?  Is it for the full sales price? 

I'm not sure what community property has to do with this.  Sounds like it was the wife's separate property, even in a community-property state.  (And West Virginia is not community property, which was my first guess about where this happened.)  And with no will, spouses inherit before siblings.  So it does sound like he gifted the proceeds to his in-laws, and the sale should go on his return, if not the estate's 1041.  

And you don't need dates of death, since all inherited property is long-term.