There are a few simple facts here. First, your mother has raised at least one child to adulthood, so there’s a good chance she does have a little more experience and knowledge in some areas than you do. Second, you are your child’s mother, and as long as the decisions you make are in your child’s best interests, everyone, including your mother, should respect them.
Your mother is probably transferring her emotion and experience from raising you to your child and that’s perfectly normal. It can also be a good thing in some ways as it means that your mother will be as careful and loving with your child as she was with you.
However, if you disagree about minor or major issues about childcare, then you need to make sure that you talk about it. Set ground rules and make them clear. These could be about anything from which snacks your child has to what type of discipline your mother uses on him or her. Assert your own desires and make sure that while you value her role as your child’s grandmother, your mother, and your child’s caregiver, you are your child’s mother and therefore have the ultimate say in what your child does and how he or she is raised.