who to ask for a reference?

I got my dream job. I got a verbal offer, they are checking references and then a written offer will follow.

I gave them 2 references from previous jobs, one of these can be hard to reach. They said they left a few messages for her and are waiting to hear back. The other one gave a great reference.

Now, we are waiting. She may call back, but I am just planning what to do if she doesnt call back.

Neither reference is from the job I have been at for the last 2 years (I am still there on a per diem basis-say 2 shifts a month so they are my "current employer").

So I figure they may want to speak to someone at that job especially if reference #2 doesnt call back. I am fine with that but here is the problem:

The facility is very small and my boss (who is very likely unmedicated bipolar) was fired 2 days ago. She was the boss I reported to. Every place wants to talk to the person you reported to-not a coworker. She did like me but she is very unstable and I feel bad calling her now and asking for a reference at this time and with her state of mind-who knows what she could say. Plus, she may not even answer the phone as she is very upset.

There is no one else who I really reported to there. There is the administrator but since I worked nights only, I never ever saw him-like 2 times in 2 years. He doesnt know me well but he does know that I have never had any problems or absenses at work.

Or I could ask the coworker who is temporarily taking on the fired boss' job. But she really has not supervised me but she does have a good idea as to the type of worker I am etc. We have worked together for 2 years.

I REALLY want this job.

So, who do I ask for a reference?

Fired boss?

Administrator?

Temp boss?