My guinea pig has died and now her sisters very loney what should you do?

Get her a girl companion. OR a *fixed* boy companion. Once you have a girl and a boy, you can never add another boy. You can have multiple girls, or multiple girls with one boy. OR multiple boys, as long as each addition is added as a baby, not yet at puberty. But if there is ever one or more girls, you can't have more than one boy, no matter what. Even in even numbers, the boys will fight over the girls.