What is it with some people?

Alright Frankie, is this woman your sister or something. :D
To answer your question, it would cost me the fuel and time, so figure a 25 mile round trip and about an hour or so total. (20 min each way and probably 20 to recover everything)
Normally it would be coming up on 80 bucks. (If it were a std paid service call)

Then next time she needed something and stomped her feet and threatened us she would expect me to do it again, and probably even tell her friends she found somebody they could get to fix things for nothing if they threatened us enough with bad publicity.
Right now the worst thing she can honestly say is we wouldn't come out and help her for free.

I don't do well with threats and demands without at the very least being payed for it, and even then it's get the job done and I'm gone. (may not ever go back either)

You are correct that she is an older woman with little knowledge and needs help, but that isn't my problem when the trade off is taking from my own family.
Tell ya what, send me 75 and I'll go do it for her and tell her you felt for her.:D JK:-)

We don't do this for fun or entertainment, but to pay our own bills, and customers will do what you teach/allow them to do.
Karma isn't accepted as payment at the bank so far.

Like I tell my wife "This is not a customer, because customers pay for services."

This is not my normal nature, but it IS what I have had to learn to do to pay the bills and not get taken advantage of.

But I hear ya.

I operated a small business for 22 years after retiring from IBM. I know what you're talking about, I just look at at things a little differently. Especially with older folks, and computers. I never lost a dime taking care of people, even when they were wrong, or unjustly blaming us for something we were't responsible for.
It's Just a different business philosophy, that's all. .
Nearly every time I did something like this over the years, it turned out to eventually work in my favor, either with more word of mouth advertising, or more business, down the road form they customer, or a friend or relative of the customer.

Best wishes for the future.