My mom hates the squirrels too. They clean out her bird feeders. The grandkids bought her a supersoaker and she fires on them from the family room window.
Tell your mom that there is a kind of seed that squirrels don’t like. It is safflower seed and I actually watched a squirrel take a seed and spit it out. The squirrels have never gone back to that feeder again.
I have a feeder with regular black oil seed hanging from a pole. I spray the pole with Pam cooking oil spray and watch the squirrels climb up and slide back down. ; )