Beyoncé turned 42 in style with a surprise serenade from Diana Ross on Monday ... World Tour in Los Angeles on Monday to sing "Happy Birthday." Stepping out in a sparkling black and feather ...

"I think she's going to go all in, which is exciting," Evan tells PEOPLE of his legendary mother Diana's planned birthday celebration ... Evan is more than happy to see his mom continue to thrive ...

Although the American Fiction actress wasn't able to spend Diana's birthday with her due to her work schedule, Tracee made it up to her by yelling out, "Happy birthday, Mom!" while live on GMA.