If she has been receiving dividends all along and is shown as the shareholder of record by Standard Oil, then she can contact the investor relations of Standard Oil (or whatever the company's name is now) and ask how to replace her shares. There is a fee you have to pay to insure them in the even the shares show up and someone else tries to cash them.

She needs to contact Standard Oil's (or it's successor firm's) transfer agent.

You will need to contact the Investor Relations office if they are still in business. If not, you need to research to see if the company was purchased and if so by whom. Then contact their Investor Relations department. If they just went out of business then the stock would be worthless and it doesn't matter.

standard oil

http://www.scripophily.com/ they will do the research properly for you for a small fee