If you would like to have a check of what's running on her PC, run the script Silent Runners (link). It's pretty good at finding everything that automatically runs when switching on the PC and useful for hunting unwanted applications such as malware.
However, the only sure way you will be able to eliminate any potential tracking is if you do a complete wipe and OS reinstallation on the computer. Then after reinstallation, have her change all her online passwords (e.g. e-mail, social, etc.)
For her router, I would also suggest doing a factory reset, as it's quite easy to remotely monitor some routers with a simple configuration. Some routers can be reset to factory default by holding the 'Reset' button in with a pin for ~10 seconds. You'll need to reconfigure it with the ISP details again.