Context not clear to clarify what is right or wrong.

Question

Yhere is nothing in the context and no hint as to why either answer could or could not be correct._______ il ne vienne pas?How come he's not coming?Comment ça se fait qu'Comment ce fait-il qu'

Accepted Answer

Bonjour Ian,
As Maarten and Chris mentioned both are correct. 
As per the lesson, 'how come...?' means 'comment ça se fait que...' or 'comment se fait-il que...'
In this kwiz, if it is a multiple choice question, only one of the translations above is given. If it was a written answer, both are accepted.  
I hope this is helpful.
Bonne journée!

Answer

I don't know what the choices given were, but both answers you mention are correct.

Answer

Both answers correctly written would be right «comment ça se fait qu' » or «comment se fait-il qu' »- you can use either, the latter being more 'formal'.  However you have written «comment CE fait-il qu' » above. That would not be marked correct in a quiz.