First of all, all communication between the site and the Find service will be encrypted (HTTPS/SSL).
Secondly, the Find service will be IP-filtered for pre-defined IP-ranges from the client site.
Also, I'm assuming the Find service is protected by a host of firewall filters as well, just like the rest of the DXC services.
You can find more info about DXC security here: http://www.episerver.com/about/privacy/trust-center/security/
Our client asking regarding the security of this service URL. As if it is a two way communication, how it is secure for our organisation n/w?