@joefromchicago,
I think she means that they've never heard of the mother- they have been given her name and neither of them know her.
If this is true, it may be a case of mistaken identity. But I guess your husband has now to prove that he's not the specific 'Robert Jones DOB 8/6/64 (for example) that this woman has named as the father.
Hopefully it'll be easy to clear up - like if she sees him- she tells the truth and says, 'No, he's not the Robert Jones I meant' but I guess it could come down to a DNA test, if she sees him and she's adamant it was him she had relations with.