I have had a blood blister under my toenail for over a month. My mom told me stick a needle in my nail and pop it. Is that safe? What should I do?

Don't. After a month the blood should be dry so you will not get anything out of it. As long as no pain i would try cutting the nail back and soak in hydrogen peroxide to was out the blood. I would use an antifungal as the nail grows out.
Blister. Don't do that ! first it isn't sterile and you will get an infection. Second it may well be simply staining the nail. It is best to see your podiatrist who will care for it .