Sorry to hear about your mother’s passing. Since they requested her medical records it looks like they are looking for some technicality to deny/limit her claim. I would request a written explanation from them regarding the status of their investigation and what they are investigating.
DISCLAIMER: David J. McCormick is licensed to practice law in the State of Wisconsin and this answer is being provided for informational purposes only because the laws of your jurisdiction may differ. This answer based on general legal principles and is not intended for the purpose of providing specific legal advice or opinions. Under no circumstances does this answer constitute the establishment of an attorney-client relationship.
I would agree with david.
You can call them and simply inquire about what is going on on their end.
This response does not constitute legal advice or the establishment of an attorney-client relationship. I recommend you meet with an attorney.