Sorry for the delayed response. I typed a response and the website crashed when I tried to send it.
I have no idea why the company is just now discovering their misinterpretation of their own pension contract. However, your husband has no obligation to pay anything back so long as the information he provided to the company was accurate and he did not sign a written agreement agreeing to reimbursement at the time of the initial payout.
The company's failure to appropriately interpret their own pension contract is not the fault of your husband and he cannot be held liable for their mistake. There is little that they can legally do if he just ignores them.
In the unlikely event that they do sue to try and get the money back your husband should hire a lawyer to respond. The lawyer should be able to get the suit dismissed fairly easily and possibly get reimbursement for attorney fees if the suit is determined to be frivolous.
I cannot provide you with legal advise. I can provide you with information about the law related to your question. My answer, and any information that you can find online, should not take the place of having a detailed consultation with a lawyer in your area to advise you regarding your specific issues.
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