To narrow you in,
Without knowing what TV she has, we assume it can be controlled via Infrared.
So you would need a controller that integrates with Alexa and can be configured to send the proper On and OFF IR commands for that particular TV.
I will take a stab that SmartThings hub maybe with a GlobalCache IP to IR device.
I haven't done the research to know if SmartThings hub supports GC.
Our controller does the above but it would be more expensive but certainly would work.
Alexa will also work with the Logitech Harmony remotes. The drawback is going to be WiFi. Alexa is going to need WiFi and so will the Harmony remote. If the Wifi goes down or the change the passwords. The system won't work.