Log in as her on your device. Delete the history, turn off ad personalisation, unsubscribe and block dodgy stuff, like and subscribe healthier things, and this is the important part: keep coming back regularly to tell YouTube you don’t like any suggested videos that are down the qanon path/remove dodgy watched videos from her history.
Also, subscribe and interact with things she’ll like - cute pets, crafts, knitting, whatever she’s likely to watch more of. You can’t just block and report, you’ve gotta retrain the algorithm.
I’d be more than fine with this, I just don’t want us to hate mosquitoes into a four pests scenario.