No thee mother cannot come and take the child as long as the guardianship is though the court,if she trys just call the police,however for your protection have grandma leave a signed statement with you stating that she is leaving the child in your care while she is gone and have her put the dates down when leaving and when coming back and also tell her to give you a statement to let you have the child treated for any medical services that could occur while she is away.


