MacKeeper is NOT a third-party software offered with the official Flash Player installer. If the Flash Player installer you used also installed this, then you did not use the official Flash Player installer downloaded from adobe.com. Performing an internet search for "remove mackeeper" will return many results on how to remove this. Do the same for whatever else was installed.
Only update Flash Player from the official Adobe website. There are many sites that have Flash Player downloads available, but these are not official Adobe Flash Player installers. If you have the website you used to download Flash Player that installed MacKeeper, please private message it to me and I'll forward it to our fraud department to follow-up on.