Why does she think it's Roku - what wording was used to describe the charge?
Lots of bad guys know how to make fraudulent charges and they can call them anything they like to mask their true origin.
The credit card or bank should be able to trace the charge back to the charging merchant. I'd bet dollars to doughnuts it wasn't actually from Roku if she has no Roku or even know what a Roku is.
Of course another possibility is that it really is a Roku charge that resulted when another user of her card, or somebody who has stolen her info, used it as a payment method on an actual Roku account.
Roku Streaming Stick +, 3810X, Ser YH0059427035, wifi - Samsung UN55ES6100
Roku Streaming Stick, 3600X, Ser 5S56D8240827, wifi - JVC EM37T
Well after working with her a little more (she is very tech illiterate, by her own admission!), She does indeed have a Roku account. We just have to reset her password so she can get in.
The bank charge specifically says Roku though and her bank agreed that it was legitimate.
So, my next step is to get back into her account that she didn't remember she had because she has a TCL RokuTV, and find out what it is. She loves alone, so she claims it wasn't her doing, but we will see!