A persons last will in testament is their final say in this world, and it should be respected unless of course these children feel she was not of sound mind,(and this can be substantiated) this or suspect foul play at the time she made her will.
Times are bad when even your last will and testament isn't worth the paper it's written on... if it turns out this old woman was of sound mind, this and made a conscious decision not to leave her home to her children, irrespective of her reasons this has to be respected.
She could have left it to the dog-poop federation and my opinion would be the same.
If it can be proven she was going a little funny towards the end, this and changed her will at a time she had began losing her faculties, (had began dementing) then fair enough, perhaps they 'MAY' have a case, but otherwise...I cant see much point robbing or sending letters of demand to the dead.
Ps, who doesn't have an autistic child in their family these days.
Why should their personal circumstances make them more entitled to property which doesn't belong to them?
It sounds like they are trying to make excuses for why they believe they are entitled their mums deceased estate.
Perhaps they were a pack of A-holes, this or she thought they would squander it.