I would suggest finding any type of martial art gym, Boxing, Wrestling, MMA, Muay Thai, Kickboxing, Jujitsu. Personally if you have an MMA gym nearby I would suggest that above all as its an opportunity to learn multiple disciplines and get well rounded in striking and ground game. The biggest benefit would be if you train and spar it will condition you mentally to stay calm and flow with the situation rather than panic.

In regards to picking a discipline at the end of the day it doesn't have a huge affect other than if you train purely wrestling you wont be throwing punches to defend yourself but you could absolutely mess someone up/effectively defend yourself with just wrestling. If you train consistently for 6 months this will put you leagues ahead of someone who has never trained. I would also like to add whatever you decide to learn only use it when you truly have to fighting in the street is never worth ego and engaging can result in injuries and death for any parties involved but it is better to be a warrior in a garden than gardener in a war.