Is Selena Gomez's mom named Mandy Teefy, Mandy Cornett, or Mandy Gomez?

Ok, I know this is a random question, but it just came across to me about what Selena’s mom is named. I have heard Mandy Teefy, Mandy Cornett, but Mandy Gomez the least. Also, is Mandy her name or is it a nickname? If so, what for? I’m just pondering this simple question, any answers?