The problem she faces is contractual really...it is contract
law that governs this insurance
program. Basically, the policy that the department uses is to limit benefits to a spouse who is not a "dependent" (however they choose to define dependent) there is not much she can do if she does not meet the definition.
In other words, if the policy defines dependent as someone who shares the same roof the majority of a given year, and she does not meet this definition, then the policy department can rightly deny benefits.
The only way to challenge in this instance would be if you could prove that the department is not following its policy.
Another example, say the policy defines dependent as someone who shares the same roof the majority of a given year. And lets say, for arguments sake, your mom met that definition (she did share the same roof a majority of nights in the past year...again, for arguments sake). In such a case, she could sue to force the department to follow its policy.
But what you describe? It sounds like she is not a dependent as far as the policy goes...
If that is the case? There is nothing under the law she can do to force the department to insure her. Even with her health issues....that is since the department is free to enforce its policy.
Now...I mention divorce since that is one way to force the spouse to help pay for this problem. The divorce court has the power to order support...so the court could, for example, order him to pay her support to help her cover her insurance expenses she will not incur due to loss of this insurance benefit.
But this requires she file for divorce...and find a lawyer to help her in the process.
So it may not be worth the effort (to hire the lawyer and sue for divorce and support).
I am very sorry to have to bear bad news. I wish that there were some legal recourse available against the department, but what you describe, I do not believe that is the case
Please let me know if you have more questions...happy to assist if I can