Final answer:
The most appropriate action for the social worker is to offer conjoint sessions to the client and her husband to address the psychological and interpersonal aspects of the situation and to provide education on the impact of diabetes on sexual function.
Step-by-step explanation:
The social worker's most appropriate action for a married woman distressed by her husband's recent inability to sustain an erection due to his insulin-dependent diabetes is to offer conjoint sessions to the client and her husband. This approach addresses both the psychological and interpersonal aspects of the situation and recognizes the role that chronic diseases like diabetes may play in sexual dysfunction. It is important to explore the couple's feelings and misconceptions about the impact of diabetes on their relationship and provide education, thereby potentially reducing the wife's fears that her husband's difficulties are related to a lack of love. Educating the couple on how diabetes can affect sexual function and addressing emotional concerns through therapy can be valuable steps towards emotional healing and relationship improvement.