What to do about trouble brewing on the horizon?

My mother and I go to church every week. For the last few months an elderly gentleman has been sitting with us. I think my mother has become secretly smitten. For some reason she has gotten it in her mind that the gentleman is interested in another lady in the church -- a very sweet, attractive lady. She has invented stories on how he likes her and has asked her out. She talks of how the woman apologized to her for something, and she sure it was about the man. I'm baffled. The man is in his mid-90s and doesn't show anything but friendship toward women in the church. I doubt he is overly interested in women, since his health is not so good.

I love the idea of romance for older people, but I don't like the way this is going with all the suspicion and confabulation going on. I get the feeling that my mother may have invented a relationship in her mind that is being threatened by this other lady. My mother has known this woman for many decades, but she is now being cast as the competition. Telling her that the man is not interested in women, and that he and the lady are just friends, doesn't help. She may accept it for a minute, then go back to her strange ideas soon.

BTW, nothing is going on between anyone. It is just people who have known each other for years. All of this is being built in my mother's mind. I am troubled by it, because I see a lot of potential embarrassment and hurt coming from it.