Home is owned by husands sister, mother of husband has power of attorney, can wife be made to leave since she originally moved out in Feb of 10, and moved in supposedly temporarily in September of 10, promising to pay $400.00 rent per month as since sept only 500 was paid. Divorce to be soon, wife refuses to work or contribute to household husband in debt due to major surgery in sept, comp payments have run out, and no insurance.

While they are married, I don't think you can evict the wife and not the husband. So he needs to file for divorce and then she can be told to vacate and if she refuses be formally evicted.

Is the husband also living there ?

If the husband is living there, you will have to evict both of them

If husband is not living there without husband, she can be evicted