Dreams involving family members, especially those who have had a significant impact on our lives, can be quite powerful and often reflect our emotional struggles and unresolved feelings. In your dream, being trapped in your grandmother's messy car may symbolize feelings of being overwhelmed or constrained by your past experiences and relationships. The messiness of the car could represent the chaotic and difficult environment you associate with her, as well as the emotional baggage you carry.

The traumatic imagery of your grandmother harming animals may reflect your feelings of vulnerability and helplessness in situations where you feel threatened or unsafe. It could also symbolize your fear of being exposed to things that disturb you, particularly if they involve themes of death or violence, which you mentioned you find distressing. Your grandmother's actions in the dream might represent unresolved anger or fear towards her, intertwined with feelings of helplessness.

Seeking solace from your mother and being met with dismissal could indicate a longing for support that you feel you haven't received, reinforcing feelings of isolation. This part of the dream suggests a desire for validation and understanding, yet encountering emotional neglect or rejection instead.

Overall, this dream seems to be a reflection of deep-seated emotions regarding your family dynamics, feelings of being trapped, and the need for support. It may be beneficial to explore these feelings further, perhaps through journaling or speaking with a trusted friend or therapist. Understanding these emotions can help you find a path toward healing and empowerment.