That is quite possible. But it strains credulity to not even make an attempt to communicate for "months", then act all shocked and shaken when the old dear ends up dead. Laura could easily have hired a service or asked a neighbor to at least check that Mom was still alive once a month or so.
Old people get "grumpy" and can be unpleasant, but they need the help of the children more and more. That seems to have been lost on Laura. Maybe the "care" Laura provided for her (if there was) is the perp. Funny, I never seem to hear Laura discussing the problems of the elderly. It's usually the pregnant teen or philandering husband getting her two bits. Could be a ratings issue.