Hi Sue, Can you make the question a bit more clear?
Is your mother shown as married to her daughterʻs husband? The link to James Lewis does not seem to match your question.
Was she instead not married to her daughterʻs father? That would be easy to fix, all you would need to do is go the the motherʻs profile edit page and on the right had side find the spouse and edit to change to not married. The father would still be the father and the mother would remain the mother and no marriage would show up.