Cleaning up a compromised Windows 7 laptop
Solution 1:
The direct answer is no - you cannot be confident. As @Moab says, if you have been compromised, there is no way to ensure you aren't still compromised. If the system owner can live with possible on-going compromise of their data and any accounts they access from this machine (banking, social media, etc), then what you've done is fine. If they are not, then it is time to rebuild.
But I would make sure the end user understands and makes that decision.