No you won't get gyno on 50mg or even 150mg/day of Ox. Gyno is caused by estrogen and your sensitivity to it. There is no conversion to estrogen with Ox.
No need to worry about aromitization with anavar AT ALL.
As for winny, nobody takes enough to notice any arimotization anyway. I'm talking around 300mg/day, then maybe you will see have some aromitization from winny...along with the need for a liver transplant as well though, lol.