They proved that they were just as awful as the things that they accused their mother of. They did not have to write an obituary. They have failed the 'discretion is the better part of valour'. These would be people in their sixties. I have to wonder, who brought them up with such bitterness.
Their maternal grandparents brought them up. Looks like they didn't have anything good to say about her either. When NO ONE has anything good to say about a person, maybe there's nothing good to say so people just go with the truth.