Final answer:
Millie is likely experiencing denial, the first stage of grief, where individuals have difficulty accepting a significant loss, serving as an emotional defense mechanism.
Step-by-step explanation:
Although Millie's grandmother died several weeks ago, she continues to ask her mother when grandma will be back to visit her. Millie is most likely in denial, which is the first stage of Elisabeth Kübler-Ross's Five Stages of Grief.
In this stage, individuals often have a hard time accepting the reality of loss. It is a defense mechanism that buffers the immediate shock, numbing us to our emotions.
Over time, as denial fades, acknowledgment of the loss and the pain it brings comes to the forefront, signaling progression to the subsequent stages of grief.