I got Ending C.  My biggest problem with this play through was I missed out on saving 50 survivors, in the pause menu it said I saved 49 but when I got to the end of the game it only gave me credit for 36!!  I also couldn't get the lady on the walkie talkie to spot the last survivor, granted I had only about 2-4 hours in game time to save that person I still would have liked the opportunity.  Also I only got to the 2nd day of the story mode when I failed it and figured I would come back later with more pp, still I didn't think this would effect my 50 survivor achievement.  
 
So after thinking about it is it possible to get the save 50 survivors in your first play through?
 
Also to get the 10 psycopath kill did you have to kill the gun men on the outside of the mall? I was kind of just running past all of them.
 
I really thought I would get these 2 achievements because everything the lady on the microphone brought to my attention I did.  I didn't lose any of the survivors she brought to me (no defects), I beat all of the psychopaths that I came across and thought I was doing a perfect run with out actually finishing the actual story mode part...  Only thing I did not have time to complete was that damn poker game!  I had 1 person left to strip when I got interrupted by the ending, could that have with held any information from the lady on the microphone?

On my first actual attempt at playing through the story I got over 50 survivors, as I got the 50 survivor achievement earlier than the end. There are a certain number of survivors that don't show up as missions you just have to bump in to them. There's also snowflake. The 2 army guys left outside the mall are actually survivors but they just shot the crap out of me so I couldn't save them.

Yea I'm guessing I missed a few of those then, I only really went after what the lady on the microphone came up with.  Still came up with a hell of a lot of survivors doing it that way.

"  I got Ending C.  My biggest problem with this play through was I missed out on saving 50 survivors, in the pause menu it said I saved 49 but when I got to the end of the game it only gave me credit for 36!!  I also couldn't get the lady on the walkie talkie to spot the last survivor, granted I had only about 2-4 hours in game time to save that person I still would have liked the opportunity.  Also I only got to the 2nd day of the story mode when I failed it and figured I would come back later with more pp, still I didn't think this would effect my 50 survivor achievement.    So after thinking about it is it possible to get the save 50 survivors in your first play through?  Also to get the 10 psycopath kill did you have to kill the gun men on the outside of the mall? I was kind of just running past all of them. I really thought I would get these 2 achievements because everything the lady on the microphone brought to my attention I did.  I didn't lose any of the survivors she brought to me (no defects), I beat all of the psychopaths that I came across and thought I was doing a perfect run with out actually finishing the actual story mode part...  Only thing I did not have time to complete was that damn poker game!  I had 1 person left to strip when I got interrupted by the ending, could that have with held any information from the lady on the microphone? "

oh that might be why I have the penalty damn!  I was really hoping to be done with that achievement before my next play through, i guess not.

I got the survivor achievement on my first playthrough (and rank S). I never ran into any random survivors, nor did I manage to even find Snowflake and the other guy (didn't know the game had random events until later on), but if you just follow all the calls from Staycie, you shouldn't have a problem finding them all. 
 
I never found the Poker players either, so if you just time your missions well, you should be able to. Did any die?

Do you mean Ante Up? If so, that's not necessary to beat the game with an S rank and it doesn't give you anyone else. I played eleven turns of it and figured it was a waste of time. But like I said, I never found any random survivors. 
 
I think your main issue is that you only made it to Day 2. If you got through the entire 72 hours, you're presented with more survivors, and psychopaths too. So that could be your issue for both achievements.