The detox footpads are a money making scam. Yes they work, but think of the amount of toxins in your body and how small the patch is. It isn't enough to significantly reduce your toxins. They are so expensive, so I would say, save your money on those and when it all adds up (and not slowly), go to a spa and get a detox body wrap which can be done all naturally and will definitely help you.
I don't want to discredit your mother, but there are other reasons why she might be feeling less anxious, plus buying the pads and doing something for herself like this is probably helping her.
Maybe you both could do a day at the spa