Latter End by Patricia Wentworth
Things had never been quite the same at Latter End since Lois had taken over. Suddenly life seemed to be an endless succession of bitter family rows which Lois, needless to say, invariably won.
More than one person at Latter End found themselves stretched to the limit by Lois and her bullying, and it was only a matter of time before somebody snapped. It was unthinkable of course . . . but if anyone ever murdered Lois Latter, it would be very embarrassing to discover just how many people might have wished her dead.