Does this document have any worth?
The patent itself has expired and cannot be enforced against anyone who might otherwise be an infringer. If there have been an unbroken string of "follow-on" applications ("Continuations" and "Continuation-in-Part") there is a very slight chance that some patent rights may yet exist (although if I think about it, probably not since the changeover to "twenty-year term from filing the application" happened more than 20 years ago – although your grandfather's patent line might be "grandfathered" in :-) ). Essentially, the invention has entered the public domain and is free for anyone to use. That was the bargain your grandfather struck with the government – in order to obtain a limited term commercial monopoly from the government, he agreed to disclose the invention to the public so that anyone may make and use the invention (only subject to his patent rights while his patent term existed, and thereafter for free forever).
There may also be some value as prior-art -- namely to help invalidate someone else's patent if they are asserting that they have existing patent rights covering the same invention (or an obvious modification). But again, as a public domain document, easily obtainable by a search engine, the document itself may not have any intrinsic monetary value.
Still, I am happy for your family's pride.