Dreams about saying goodbye to a loved one, especially a parent, can be quite emotional and may reflect your feelings about loss, change, or transitions in your life. In this case, dreaming of saying goodbye to your mother as if she is dying could symbolize several things:

1. Fear of Loss: This dream might indicate a fear of losing your mother or someone you are close to. It could also reflect your anxieties about the health or well-being of loved ones.
2. Change in Relationship: Saying goodbye can signify a significant change in your relationship with your mother. This could be related to personal growth, independence, or evolving dynamics as you navigate adulthood.
3. Processing Emotions: The dream may be a way for your subconscious to process feelings of grief, whether related to your mother or other aspects of your life. It might suggest that you are dealing with unresolved emotions about past experiences or relationships.
4. Symbol of Transition: Goodbye can also symbolize a transition or the end of a particular phase in your life. This might relate to personal development, moving on from certain beliefs, or letting go of past experiences.

To gain more clarity, consider the emotions you felt during the dream and upon waking. Reflecting on your current life situation, relationships, and feelings about change can also provide valuable insights. Engaging in conversations with your mother or loved ones about your feelings may help you process any underlying emotions.