Am doing the right thing by turning down a babysitting job?
Why are you going to turn down the job?
The mom told me what it pays and it's really low.
It's fair to turn down the babysitting job if you aren't getting paid what you think you should be. You don't have to take every job that is offered to you, and low pay is a legitimate reason to turn one down.
The mom will tell everyone  that I'm a horrible person for turning down their low paying job. This is so unfair.
It doesn't matter what she will say. You're within your rights to turn her low paying job. Be assured nobody is going to believe her stories.