Answer:
Empty nest syndrome
Explanation:
Empty nest syndrome is a common type of crisis where one's sense of identity and purpose in life is being challenged.
The name of the syndrome refers to the fact that once somebody's children grow up, the house (nest) becomes empty and the parents have to live on their own again.
Marie has devoted most of her life to her children and taking care of them had been her sole purpose in life. Left without them she feels useless, abandoned and she does not know what to do with her life.
To cope with her situation, Marie should start to live her own life, apart from the old one. She should get to know herself better, find new friends, hobbies and activities that gets her out of the house, she may get involved in voluntary or community work where her needs to help others would be satisfied.