In November, I made a complaint anonymously concerning my direct supervisor and the fact that she jeopardized my safety and other coworkers. The other part of the message was that she was demotivating, dishonest, etc. No one ever contacted me or others concerning this complaint; although anonymous, could have been questioned by superiors regarding all those under her direct report.
Time passed and out of nowhere, she asked me for my resignation last Friday. I refused and said that I would like to consult an attorney. She informed me a few days later that the VP, myself and she would be on a conference call. This is her modus operendi when she wants rid of someone. I contacted the VP of HR and Operations and stated that I would not be on the call, unless I could have a conference call with the both of them. The VP of HR said that the Operations VP would call me that day to set up a meeting, which never happened. I decided to give my notice rather than continue to work in a hostile work environment and face retaliation.
What are the rights for Unemployment and is this a possible law suit?
I would appreciate feedback.
Regards.

You always have the right to file for unemployment. It will be the decision of the state whether you receive it, not your employer. The fact that you resigned makes it much less likely that you will receive it.

Nothing you have described in your post gives you grounds for a lawsuit. I'm assuming you feel you were going to be terminated or otherwise disciplined because of your complaint about the supervisor. On the basis of the information you have supplied, even if you are 100% correct about that, it does not reach the standard for illegal retaliation. You are in an at-will state; you can be fired for any reason that does not specifically violate the law.

BTW, what you describe does not come even remotely close to meeting the legal definition of a hostile work environment.

If you left an anonymous message back in November, what makes you so sure that this is the reason for the meeting now? How would your manager even know it was you that left the message and why would she wait several months to retaliate if she did?

You also don't know for sure that you would have been terminated as you resigned before the meeting, including the one you requested.

You can file for UI, and in MD, who knows, you may get it, but I wouldn't hold my breath.

Nothing you describe indicates anything illegal happened.