How Would You Handle a Customer Trying To Blame You For Another Person's Work?

So here's the situation - we had a customer we did a handyman punch list for. She previously had some really bad work done at her house and we were fixing their mistakes. Almost 10 month later - She claims that we installed a cooktop using silicone however my guys take very diligent notes and pictures and I have no record of that installation happening. I double checked with the guys and they didn't do it. Something like that would have taken some time and they would have remembered. 

Honestly I don't mind losing her as a client because she's wasted a lot of my time having my quote jobs she didn't end up doing but how do you tell someone she's mistaken when she is very sure we did it. 

I thought about sending her screen shots of our time stamped notes but I can't tell if she lying or not. What would you do?