Deductions & credits

One more nuance to this question.  Specifically, my mom's appreciated stocks were held in an ancient trust set up for her by her parents.  Because of the terms of the trust, when I received the stocks from the trust THE BASIS could NOT BE UPDATED!!  Therefore the Cap Gain is massive (e.g. P&G stock @ $ .75 acq 1956).  

So, is this technically "inherited"?  

What cost/acq. date do I use?    The actual basis I am subject to or date of death.?   

Your perspective very much appreciated!