I have pdf's going back to 1998 or so, but sometimes not the 1040s filed with extensions, or the 1065's and 1120's.  And of course that's usually what people need.  

As I was saying before Intuit decided not to let me answer the original question, what the client received was no doubt a "subpoena duces tecum," which means "bring some stuff."  And usually it's not the preparer they want, it's just the documents.  And a convenient time and method can be arranged to get it to the lawyer who asked for it.  But first the client should be made aware of the request, so they can challenge it.  That's why others are suggesting you call your E&O insurance carrier.  They want to make sure you don't get in trouble with your client by handing over something that is privileged.

Usually witness fees and copying expenses are paid to nonparties who respond to a subpoena.  There might have been information about collecting, served with it.  I think in federal cases they attach a check.