This is a very frightening dream, but I think you can rest assured that your grandchild is in no actual danger. The grandchild in your dream probably represents yourself, that is, your inner child. This is the aspect of yourself who remains vulnerable, innocent, curious, and perhaps a bit mischievous. The dream could be telling you that your "adult" self, the responsible, hard-working, serious aspect of yourself has been allowed to steal away your sense of fun. It sounds like it's time to loosen up and let yourself be a kid again, at least once in a while. Especially when you are with that grandchild.
Dreaming that someone has been kidnapped suggests that the dreamer feels that person has been emotionally distant, and not available to the dreamer.
it means that you might lose something that you care about very soon so you should keep an eye on what you need
To dream that someone has been kidnapped, indicates that you are not letting characteristics of that person be expressed within you. You are trying to contain and/or suppress those qualities of the kidnapped person.
it can mean that you sense danger for you child
Dream child or little dream
It is natural to dream about people in your life, so this dream might mean nothing beyond your familiarity and affection for your friend's child. On a symbolic level, the child could represent either your friend or yourself in the dream. Beyond that, the meaning of the dream depends on what is happening in the dream and on the emotions you experience as the dream takes place.
The child in your dream represents some part of yourself that has been wounded or crippled in some way. The dream may be urging you to recognize an emotional injury or painful event that you have denied and hidden from your conscious mind.
Dreams are about the dreamer. So although you dreamed of someone else being kidnapped, the dream illustrates your own feeling of being forced to go somewhere or to do something against your will.
Dreams are about the dreamer. In this dream, the nieces represent some part of the dreamer's personality or some part of life. Kidnapping suggests that you feel this loss is beyond your control. The dream could alert you to notice and consider whether you have been neglecting or losing an important side of yourself.
It suggests that you feel as if for years - or at least for a long time - you have not been allowed to do what YOU want or need to do. You feel as if someone else is holding you back against your will. Your own mind is using the metaphor of being kidnapped to illustrate your deep feelings of frustration.
If you are having a dream about getting kidnapped, it means that you (in real life) are being forced to do something you don’t want to or are in a situation where you feel useless.
The dream expresses the dreamer's feelings and/or intuition. It does not provide direct information about the lover's emotions. The dream suggests that the dreamer is not confident in the relationship. It might also suggest that the dreamer already suspects, intuitively, that the relationship is in trouble.