Claim Listing functionality - how to send email to users when their claim has been approved or denied

We have a claim listing plugin, it allows items(posts) to be claimed by users. It requires the user to "register" in order to claim that item therefore they have to enter a username and their email.

After they have submitted a claim, an email will be sent to the admin email(us) that a user is claiming for the item and gives us the option to approve or deny it.

When we approve or deny it, unfortunately no email is sent to the user informing them that the item has been approved or denied.

https://codeshare.io/arJdnE

How could we get wordpress to send an email to the user informing them of our response?