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stock certificate in two names
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the common way to frame the "should i sell" question is ask yourself "would you buy it today at the current price".  if you wouldn't,  sell it. is sounds like this may be a paper certificate.  you will have to research how to present the certificate to a broker to trade it, or if the company has a direct shareholder program.  i have periodically been offered to sell "odd lots" to shareholder programs which, if one exists, may be less hassle than other options.  as a part of this, your mother's estate administrator should decide if the estate is selling it's interest, or giving it's interest to heirs before the sale.
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