If she refuses, hire a locksmith and bill her (warn her first). 

Work up a spreadsheet of the court costs, attorney fees, moving fees, repairs, locksmith, and most important lost rent due to nonpayment during this process.

I have a locksmith going to fix it now. 

I would calmly explain you have changed the locks and the old tenant does not have a key however if he feels uncomfortable (and people have their quirks) either offer to change for him or have him document a locksmith changed and give you a key.  

This can depend on what kind of response they send to the court, will they put any money into the registry and/or are there any holidays.If the eviction runs its course, at the end the sheriff will come out and you will meet them there with a locksmith and maybe an extra hand in case there are items left in the house.

If your keys don't work, call a locksmith.

if I told you I hired a locksmith.... told him I had just bought it at auction...

We never lock that door.On contacting the landlord was told we're responsible for the locksmith.  

If there is one, then write it down and keep that in a safe place.First house I bought, I had to break in through a window (small town, Labor Day weekend - Locksmith's voicemail said he went fishing LOL). 

If the key don't work, bring a locksmith.