Getting a subpeona is always scary, but don't worry Nance. It's a good thing in this case. Just to put your mind at ease, the DA should brief you before going into the courtroom as to what is going to happen, and if he doesn't, it is most certainly your right to ask him what to expect.
Like someone said above, bring his pictures with him. Might not hurt to take a cane along too!!

(and I'm assuming Tud is cane free at this point, but he may very well not be)
And like Lab Dad said, it may very well not even get reached that day, and Tud may get another subpeona for a return date.