Most of the candidates are required to send their job applications through email nowadays and the organizations send their response in less than a week in most cases. You are informed of the required documents or the decision of the company in the response but sometimes there is a delay from even some of the best companies.
You should send an email for apology to the applicant in this case. The first paragraph should have the apology from the company and the dates on which the application was sent. The second paragraph should have the reason for the late response and the concluding text should have the details of the email you are sending.