My Mother in Law is 75, she has significant cognitive decline. My cousin keeps trying to find out from her how much money she has, and has been asking my husband about POA and how they work. How can I make sure my cousin does not get my mother to sign a new POA? She really likes him, and I do not want to prevent them from going out to lunch and other things. Can I have her FL Drivers license flagged or something?
Just curious: how did you discover that your cousin is prying in your mother's financial asset status? Is she asking your mother directly? Or asking your husband?
Besides following Alva's excellent advice, I might (and probably would) find a way to have a private session with your cousin and explain sweetly that your mother's assets are private, and aren't the subject of family discussions. If you're not comfortable with a face to face talk, a nice card with very delicate advice could be sent. I do think in person conversation is better though; you can judge the other person's response.
Sometimes just a "why do you need to know" inquiry can stifle asset snooping attempts.
An alternate, more aggressive but not direct way to attempt to stop the inquisition is to ask your cousin if she's volunteering or available to help care for your mother, and if so, what can she offer in terms of assistance?
I do know though how prying some relatives can be and have had to devise very polite "none of your business" responses. I often wonder if these kinds of relatives realize how inappropriate their behavior is.
Then make sure all of that is true.
If you have not discussed with your mother POA, and her possible future needs for one, now is the time. Do you wish to do this work (it IS work); are you willing to pay bills for your Mom, keep meticulous records understanding that is your responsibility as a Fiduciary? Then now is the time to discuss this with your mother if she is of sound enough mind to do a POA and a will, etc. Are you even certain whether or not a DPOA is in a current will she may have?
The best way to avoid catastrophe is to act now while your Mother is able to understand your wish to protect her and your willingness to serve. Or at least to discuss changes you are seeing, and your wish to protect her.
If your mother and you do not have enough mutual trust to do this, then the sad fact is that she may in fact choose this cousin to be her advocate. Then, should you suspect abuse it would be your chore to pursue conservatorship in order to protect your Mother's finances and see to her diagnosis and care. Hopefully this can be avoided with some proactive honest discussion within the family.