Question
Why did Apple call one of their computers the Macintosh?
Answer
It was based on a type of apple that you eat (e.g., golden delicious, Fuji, etc.). It would have been called the McIntosh, but there were legal reasons for adding the letter "a". To read more about how the name was chosen, see this page.
There is no connection between the Macintosh name and the term MAC sublayer of the OSI networking model or the historic MAC Project at MIT. (The word "daemon" in computers seems to have originated from this MIT project.)