You have a remote employee who needs to access client files that are stored locally in your network but are not accessible through the World Wide Web. You need to establish a:

To allow a remote employee to access client files that are stored locally within your network (which aren't accessible through the World Wide Web), you would need to establish a **VPN (Virtual Private Network)**.

A VPN creates a secure tunnel between the remote employee's device and your local network, allowing them to access files and resources as if they were physically present in the office. It helps maintain security and privacy while accessing sensitive information over the internet.

Here’s a brief overview of the other options:

- **LAN (Local Area Network)**: This refers to a network that covers a small geographical area, typically single buildings or campuses. It wouldn't apply to remote access.

- **WLAN (Wireless Local Area Network)**: This is similar to a LAN but uses wireless technology. It's still not suitable for remote access.

- **WAN (Wide Area Network)**: This covers a broader area and connects multiple LANs but wouldn’t provide the secure access the employee needs to access specific local resources.

In summary, a **VPN** is the correct choice for secure remote access to local files.