no.
i think they should be sentenced to death for killing their mother. the issue of whether they experienced some kind of abuse is of no legal relevance and does not justify murdering somebody.
these were grown-ass adult men at the time (ages 18 and 21) who had the agency to get up and walk away from any sort of abuse and they instead chose to participate in an act of premeditated murder in order to take control of wealth, property and finances. that was their choice, they made it and they need to be punished for it. the narrative of abuse was and is nothing remotely resembling a convincing defence, regardless of if it's true or imagined. it's completely irrelevant.