Dumb Stock Question

I have a dumb question for anyone out there  who knows about stocks. I was just going through some old papers and discovered a stock certificate in my name for one share of Libby, McNeill & Libby that, apparently, my grandparents purchased for me the day I was born. From what I can tell, Libby was bought out by Nestle in the 1970s. The stock is actually in my late mother's name as custodian for me under the California Gifts to Minors Act. Is my one share worth anything? If so, how do I go about redeeming it?