Hi Suzanne. Can I clarify what you are asking?
1. Is it that you want to limit the choice of Moodle tools, so that they can ONLY add a H5P drag and drop activity to their course, to the exclusion of any other tool?
2. Or, are you seeking to guide them to preferentially use H5P drag and drop?
3. Did you want this change to apply to a single course, a course category or site-wide?