Final answer:
A social worker should first focus on the client's feelings about her mother's change in behavior, while offering support and understanding to navigate the family dynamics and understand the client's own emotional responses.
Step-by-step explanation:
The first step for a social worker in this scenario should be to address the client's feelings regarding her mother's change in behavior. It is important to acknowledge and validate the client's emotions, as they are a direct response to the changes in her familial landscape. A social worker's priority is typically to offer support and understanding, helping the client to navigate and understand her reactions and the new dynamics within her family. Rather than suggesting a psychological evaluation for the mother or exploring different living arrangements, which could be seen as intrusive or disrespectful of the mother's autonomy, the social worker might benefit from first exploring the client's grief over the loss of her father and her difficulty in accepting her mother's desire to move on and find happiness.