“How do I stop my child from grinding her teeth at night?”

Grinding in young children at night is quite common. This is usually not pathologic but the body's way of adjusting the bite due to growth. This usually occurs when the child is in deep REM sleep and the jaws are in the most relaxed position. They are usually so deeply asleep at that time and it does not wake them but is frequently heard by parents in another room. This should stop when the 6 year molars erupt and are in occlusion. It is most of the time not a problem

How old is your daughter? Depending on her age, this might be perfectly normal. Grinding is a part of a child's neuromuscular development. In fact, most kids do exhibit some form of grinding. Most of the time, this habit stops after they switch over to adult teeth. For other cases, we can look into occlusal guards to help alleviate the symptoms of bruxism.

This is not an easy question to answer! There are so many variables besides your daughter's age. This could be a purely dental or even medical condition. Does she sleep well, tired during the day, suck her finger(s), wet her undies over night, high stressed/pressure from siblings/parents? Are there obvious wear facets, none or ground down to the gums at the
canines or front teeth? Best suggestion would be to see a pediatric dentist.
Sorry if you were looking for a simple answer, but there is none without more information.....

Some grinding can be normal, but not if it causes pain. Some grinding is related to airway issues. Best to see a pediatric dentist for evaluation.