My little sister just graduated and she got a scholarship and she decided to take a year off fo school..does her scholarship still valid when she go to college after a year off?

That depends on the college she is going, who is giving the scholarship and the reason why she is leaving. Scholarships, have nothing to do with when you use it... usually. For example, if the person/company/association giving the scholarship said they would give her the scholarship for her las year of college they have to give it to her for that last year doesn't matter if it took one more year to get to that last one or if she got promoted one year above the one she was supposed to be they have to give it to her one year earlier, but it has to be the last year. 

So no, it doesn't matter if she takes a year off, she still has her scholarship she just needs a document that says she is taking a year off and why and turn it in to whoever is giving the scholarship.