You need no special insurance policy.
I would pay an average hourly wage with a 2 hour minimum, plus compensation for use of vehicle if a vehicle is provided.
I believe an average rate is $15/hour but it depends on your geographic location.
I don't completely understand your comment at the end. I think you should charge what your services are worth and stop concerning yourself with what others are making.
Eyeglasses can run into a lot of money depending on the prescription and extra options that are added. Your mother may have fallen prey to a good salesman. Take a look at the itemized receipt. Did she opt for the economy frames? Are there any extra options (non-standard) she added... more
Call the Dept. of Social Services in your state. Years ago, I was paid in NC for assisting an elderly person. Things could have changed now. The program was referred to as "chore provider".
Ask the person giving you this information to verify their source. If this is your client, stop working for them immediately - law or no law. Anyone who gives up their warm bed at night to be at someone's beck and call deserves to be paid - period.
There is a separate profession for that.