Would you have liked it if you were forced to default because you had a player out of town that couldn't play? The idea is simple. If they are defaulting because they don't have enough players to play a match, it is up to you to guarantee BY CODE OF ETHICS that you do have 2 players who are ready to go and play the match. It doesn't matter if you actually have to show up or not, the fact that you must have 2 ready players is the written rule to accept a default.
Sucks for her that she can't play at state, maybe she should have shown up for more than just one match if she wanted to go that badly. Also, technically speaking if you don't have 2 players that are ready for the lineup and to accept the default from the other team, you MUST as an ethical captain inform the other of the same issue and the match will be a double-default where each team loses and no one is a winner for that particular match.
Abide by the tennis code of ethics or gtfo.