If children are more willing to find their grandmother than their mother, it is because grandma took care of them more since childhood. Usually, mother plays a strict role in family education, and grandma is always the umbrella of children.
Find out what kind of reason you are first. Spend less time with the children, and the mother must put down what she is doing and spend more time with the children in the future. Motherly love is an indispensable part of a child's growth process, and it will also have a great influence on the child's personality.
If it is because of family education, then mother must communicate well with grandmother, and proper education is necessary. If children seek refuge from their grandmother when they make mistakes, they will develop the psychology of dependence, and will also make them unaware of their mistakes, which will be difficult to discipline when they grow up.