Final answer:
The dad can contribute in various ways when the mom helps shop for the dress, including budgeting, offering suggestions, providing moral support, and assisting with other tasks.
Step-by-step explanation:
When the mom helps shop for the dress, the dad can contribute in various ways. He can help with decisions related to the overall budget for the dress, offer suggestions on style or color, or accompany the mom and daughter to provide moral support. Additionally, the dad can help with other tasks such as researching dress options online, organizing the shopping trip, or assisting with any necessary alterations or adjustments.