A rosette is something which is usually presented as some sort of award, so why not say thanks to the chief bridesmaid for all of her hard work in ensuring that everything related to the wedding and hen night runs as smoothly as possible?
The red and pink colouring will really convey the impression that it is an all girls together night and the chief bridesmaid writing will make sure that everybody knows just what role your maid of honour's part has been in organising the proceedings.