Oh, boy, you've got a problem. And your husband, whose mother she is, has got to help. Insist—don't merely recommend—that he talk to her and remind her that you are the baby's mother and that no advice in the world will help the baby if you disagree with it. And have him remind her that the baby does indeed have other grandparents who also want to be important in her life.
Try hard to keep your cool and not alienate her. You want your husband to remain on good terms with his mother, and you want to do the same thing. If you are hostile to her, it could well put a strain on your marriage. Also, don't overlook the possibility she has some good ideas that might be of help.
When we are new mothers, most of us can learn from our relatives who have preceded us in this critical role. You want your baby to grow up knowing and loving all her grandparents, including the one who is now being intrusive. Try to pass some of this off as simply overly intense grandmothering. Chances are, she will moderate her behavior as your daughter gets older. If not, you can then consider more drastic steps to take.
Our parenting advice is given as suggestions only. We recommend you also consult your healthcare provider, and urge you to contact them immediately if your question is urgent or about a medical condition.