My younger sister is on her 2nd kidney transplant. Her first one was a cadaver when she was three. In her infinite wisdom, she stopped taking her meds (they caused an upset stomach) and went into kidney failure again, so my dad donated. My sister and I were also being tested as possible matches.
It's a tough procedure. Really think about the health risks and if you are ok with them. Also, think about how you'll feel if you donate a kidney and it doesn't take. That is a possibility.
It's a big surgery. You might want to hire a dog walker for a few weeks. Take it easy, and no heavy lifting for some time.
But otherwise, it's incredible of you to consider doing this for your mom. What a gift! My sister had her transplant about 12 years ago, and it's still going strong! Dialysis is not a nice life for a person. You can't travel, it's very hard on you physically etc.
Best of luck to you and your mom!