Once you use the word "reason," the words why, on account of, due to, because are all extraneous -- and wrong! "Reason" is enough.
...The reason is because he... NO!
...The reason why is he... NO!
...The reason is on account of his... NO!
...The reason is due to his... NO!
...The reason is I didn't have the money.
...The reason is that he was not there.
Just a little work on our grammar! :-)
Happy punctuating!
Margie