Should honorifics be included in acknowledgments?
In general, when in doubt, you should use the name of the author as it appears professionally. If the person in question publishes under a particular name, you should use that. The only exception is if you and the author have an existing relationship outside of this, in which case it is appropriate to use a less formal name.

You do not normally need to include honorifics ("Prof.", "Dr.", etc.) unless specifically asked to do so. 

This leads to the final point: if you have any questions about how someone should be credited in an acknowledgment, ask. They'll generally be more than cooperative.