The best approach for Danyon to thank all the team members and obtain feedback on the overall project is to: hold a review session.
A review session can be defined as a teamwork meeting that is organized to host all of the team members involved in the planning and execution of a project, so as to achieve the following:
Formally discuss about the project by sharing ideas and opinions.
Obtain feedback on the overall success of the project.
Make a vote of thanks.
In this context, holding a review session is the best approach for Danyon to thank all the team members and obtain feedback on the overall project.