This question is unlikely to have a very strong cultural context so I welcome answers from members all over the world.
I met this person (code name Jane D) when I was studying sociology at Masters level 12 years ago. She was much older and a senior graduate student in the subject, and already a very vocal feminist.
We had some social science discussions at the time (she was not part of the faculty conducting the course, and thus not my teacher) and I developed a sympathetically pro-feminist attitude which was conjoined with a new understanding of how patriarchal societies control both men and women.
We lost touch for over ten years but she has recently become my neighbor. Both she and her politico-liberal husband (read Marxist intellectual) are full-time university professors while I am doing things totally unrelated to academia these days. However she has become a friend of my mother, who knows her family from long back.
The trouble is that Jane D frequently visits my mother and whenever I meet her by chance she starts delivering strongly political speeches about feminism and patriarchy. Her tone is alarmingly accusatory and she keeps saying "you men" this and "you men" that, despite my repeated efforts to remind her that I am a sociologist myself and not at all a representative of patriarchal society.
A sample conversation which we had 2 days ago:
Jane D: you men have been keeping women down forever! Again and again I see this. You men have the steering wheel of this whole society! Is it your divine right or what? You have no right to say what women should do in this country. etc.
(I say: don't include me! What have I done? I agree with you completely so why you think you need to convince me!)
Jane D: you men are all alike. A man can never help a woman. This is another class war like Communism and we don't need your support. Without your support only the women will set themself free! (She is a radical feminist.)
It is not even a sensible political discussion, and really upsets my mother, who is a retired doctor and totally not interested in politics. She cannot be bothered about anything that distracts her from her health and her family, but she hesitates to be strict with Jane D because she considers her a friend and was close with their family from long back.
Note: Jane D is absolutely convinced that men are the class enemy of women but she has nothing against me personally (friendly enough when not politically fired up, which is like 15% of the time) -- her husband is aloof and never accompanies her on these visits nor meets with us on any other occasion. I don't really know this person but considering Jane D's personality, he is very unlikely to be of any influence in this matter.
Summary: I don't want Jane D to be talking about feminism and patriarchy all the time, and I especially resent her categorizing me as part of patriarchal society, but she resists our repeated hints and efforts to change the subject. It is not in my personality to be aggressive and clash argumentatively with her over this issue. Mother has also requested that I should not tell Jane D directly not to discuss politics when she visits us, because it is impolite from the point of view of Indian hospitality, which tells us never to offend a guest or neighbor.
So how do I diplomatically deal with Jane D's this habit of continuously delivering political speeches about feminism when she visits my home?