If she cannot install anything on the laptop, you could upload the .ISO to some web space, or host it on IIS on your computer (forwarding port 80 from your router).
You then email her wget, which she saves on the desktop. She then has to open a CMD prompt (assuming that is not locked out as well), and types in:
wget -c http://yourwebspacedomain.com/youriso.iso
Alternatively, you can use cURL in the same way, using an FTP server.
curl -o youriso.iso ftp://ftp.yourftpserver.com/youriso.iso
curl -C - -o youriso.iso ftp://ftp.yourftpserver.com/youriso.iso