Only the applicant who has received the appointment notification for the fingerprints needs to appear.  If several members of the family applied for N-400, then they will all get the fingerprint notifications.  If your father does not meet the requirements, then it is a bit too late now to worry about having wasted the money on the application since that has already been submitted and it is nonrefundable.  The USCIS will check eligibility for the naturalization and if your father does not qualify, he will not be naturalized.  As far as going or not going for the fingerprinting, it is up to him.  If he does not go, the application will eventually be terminated due to abandonment.  If he continues with the process and goes for the interview and it is evident at that point that he is not eligible , he will be denied at that point.