In Indiana if a 16-year-old girl has been living with her grandparents over one year can her mother make her return home?

Generally the custodial parent only needs to request the court for a requisition order to have the underage person returned to their custody. In a case such as this one, the grandparents could contest the filing and apply for guardianship. It is likely a judge would grant guardianship under these conditions with a main factor being the reason(s) the minor moved to the grandparents residence. The mother would not be able to enlist the assistance of police or other authorities to have the minor returned to her custody, she would need to have an order from the court.