Why does Bruno´s mother say that his grandmother would turn in her grave?

Bruno's mother said that his grandmother would turn in her grave if she knew that one of the funeral wreaths on display at her funeral had been sent by the "Fury".

There were a lot of wreaths delivered to the church and father was proud of the fact that one of them had been sent by the Fury, but when Mother heard she said that Grandmother would turn in her grave if she knew it was there.