Dreams about losing something valuable, especially an item with sentimental significance like your grandmother's locket, often reflect feelings of anxiety about losing a connection to loved ones or a sense of identity. The frantic search in your dream suggests that you may be grappling with unresolved emotions related to your grandmother's passing.

The deep sense of loss and guilt you experienced in the dream might indicate that you are mourning not just the physical loss of your grandmother but also the emotional support and memories associated with her. This dream could be prompting you to examine your feelings about your relationship with her and the impact of her absence in your life.

Consider reflecting on your current emotional state and any unresolved issues regarding grief or change. It may also be helpful to find ways to honor your grandmother's memory, such as sharing stories about her, creating a tribute, or simply taking time to remember the positive moments you shared. This could help you find closure and ease the feelings of guilt and loss that surfaced in your dream.