Mickey Mantle Billy Martin and.... Bob Watson?
 

Finger's Furniture circa 1977-78

I am not sure of the nature of your post , however, Bob Watson was signed as a free agent by the Yankees and played for them in 1980 and 1981.
As for the signatures they look good to me, however I am no Mantle expert.

I'm 100% they are real. They were obtained at a furniture store/baseball museum in Houston. I just really like the choice of guests.