Hello and thank you for allowing me to address your legal question.
Yes, a bank may cancel your debit card without any prior warning, and it may also terminate your relationship with the bank for just about any reason, except for a few exceptions relating to things like race, religion, gender, disability, etc. In this particular case, the bank probably decided that you were a risk because of the NSFs (or at the least that’s a legitimate reason to terminate an account).
I’m concerned by what you stated with regard to your father’s wife, however. If the account were yours alone, then the wife has no right to remove any funds from the account. If she did so with no authority, then the bank itself may be liable to you for the damages (and cannot charge you NSF fees). However, she acted with apparent authority (for example, if she had your debit card and the PIN), then you would still be liable to the bank, but you could sue her for all of your damages (i.e. the NSFs).
If the information that I provided was helpful, please remember to ACCEPT my post as that is the only way I will receive credit and compensation for my answer. However, please understand that my answer is meant for informational purposes only and is limited by the facts presented. Therefore, it should not be construed as “legal advice” and is not an adequate substitute for the retention of legal counsel. Thank you and good luck!