Cats are living creatures, you can't create one out of thin air and you shouldn't just keep one that comes to you as it may have an owner. Alongside this you definitely can't conjure one with magickal powers like invisibility, etc, in the spell you mentioned.
If your mum is allergic then it is best to wait till you are in a position to purchase or even better, re-home one that has the suitable patternation and temprament for your lifestyle when you have your own space and won't negatively effect someones health.
Re: spells to get cats? By: Wild120
Post # 3 Feb 15, 2018
Magick unfortunately cannot create a creature like a cat that already exists and cannot summon up a cat as that goes against the laws of nature and science.
I also agree with above you should wait until you have a place where the cat will not affect your mother's allergies