I used to use Adblock Plus in my IE 11 but found it was causing IE to stop working in Win 10.
In it I had our friends at
www.majorgeeks.com white listed as well as a website I occasionally use which has dynamic data that was blocked otherwise.
I have uBlock Origin installed in my Firefox but as I rarely use Firefox, I just have uBlock installed as a matter of course.
These may help your friend.
I know what flashing images can do sometimes as years ago it had the effect of producing an epileptic fit in a then young friend of my sons.