Or tell the neighbor that you’d like to help, but really can’t. The liability risk to you is substantial, since you’re not a bonded tax practitioner. They can go to the library, the American Legion, a senior citizens’ agency ...
I won’t do taxes for people I don’t know well. I tell them to go to the senior center or to a bonded preparer, and also tell them I will not sign, so if they don’t like the conditions, they are free to go elsewhere.
At least with the information online, I don’t have to be confused by the written instructions. Unlike a checkbook or bank account where I’m on my own with a mind that throws tantrums...