I checked from internet it is 9.11.2014. Do the rules apply the same dayI had found some IRCC Backgrounders that suggested the 5-years' ban came into effect towards the end of 2014.
Nonetheless, maybe you can email your local visa office to confirm whether the 2-years' ban or the 5-years' ban applies to your mom's case. You must include a copy of her previous TRV refusal letter that states she was banned for 2 years
But the letter received says 2 years