Stepped up basis of stock following death of Joint Owner

I own several publicly traded stocks that my parents bought for me when I was a child.  Originally, they were owned via a UGM account.  But when I became an adult, the stock was transferred to a joint account WROS owned jointly by me and my mother (my father died many years ago).  My mother died in 2020.  Question:  Do I get a stepped up basis in 100% of the stock since 100% of the purchase price was paid by my parents?  

 

Thanks!