Is the father obligated to return his daughter to her husband's home in compliance with the Almighty's saying, "Do not expel them from their homes, nor should they leave," or should the husband go to the wife's father to resolve the dispute between them?

It is obligatory for your niece to return to her husband's home, and it is not permissible for her to remain in her father's house without her husband's permission, unless she is being harmed. The husband is not obliged to go and bring her back as long as she has left the house without a valid reason. However, it is preferable for him to go, out of consideration for custom. Some wise individuals should intervene to reconcile between the spouses.