My mom has a B4, but I'm no longer on B1

Hello,

I came to the US in 1999 on a B1 Visa. My mom accompanied me on a B4 Visa (Dependent on B1).
Now, 4 years later, I'm here in the US on a H1B. My mom is intending to visit me. Does she need a new B2 Visa or can she come on her old B4? My B1 expired long ago.

Please do respond to this,
Thanks,
Rajashree