You and your husband need to speak about this away from your MIL. This is going to test your relationship. You both need to come to an agreement on how to move forward. You and your husband need to decide what she is responsible for. Cleaning up after herself only? Helping out with other cleaning/gardening/cooking to contribute to the household she is enjoying for free?
Your husband needs to be the one to communicate to his mother what the two of you decide. He will need to respectfully and calmly set clear expectations of what you both require of her going forward and what will happen if those expectation are not met (i.e. move out). If she does not begin to contribute, your husband will need to provide her a fair move out date. In the meantime, you and your husband should help her organize her finances and help her find a place to live on her own. Surely that is her goal anyway, I'd hope....
If you and your husband can not agree on what you require from her, or what the consequences will be, you will continue to be her full time house keeper, and she will be living smugly at your expense.
I know of what I speak. My mother let a male "old friend" move in with her to help him out through some hard times he was having - financially broke due to a bad fall (that put him in the ICU for 2 mo) because he's a drunk. They were giving a romantic relationship a try, and when he moved in he was all full of promises - he'll the be "house husband" and take care of the cleaning etc, he'd cook, he'd do yard work, he'd be Mr. Fix-It. He lied, and lied and lied about everything to get in the front door.
Well, none of these things came to pass, of course. In fact, turns out all he wanted was to live rent free, use my mom as his house keeper (while she worked full time and he didn't work at all), and "borrow" money from her. When she was diagnosed with breast cancer, and home to recover from her surgery, he moved his just as lazy daughter and her 3 yo in for a week, my mom finally told him he had to get out. While she wouldn't kick him literally to the curb (we would have) he was finally sober long enough to find a place to live.