What’s a (NEGATIVE) slang word for (an old biddy) a nasty, grumpy woman whose adult children are under her control, she’s obsessed about her image only and wants to be in charge all the time? The word will be used for a female viper, the MOTHER of vipers, so it can be very nasty.
Thanks in advance
Maybe “a shrew”? @Alan, @NearlyNapping, @Arinker can you help please?
Off the top of my head I would say - vicious old bag but for one word I would suggest - hag. Incidentally ‘old biddy’ is an affectionate term.
My first thought is “witch”.
Maybe a “domineering narcissist“.
I’ll give it a little more thought for something more colorful.
Here are a few more thoughts. Ultimately you need to develop something that fits with your story.
Tyrannical old hag/witch
A T. Rex of a mother
Tyrannical old reptile
Reptilian Lucretia Borgia
Reptilian tyrant
Tyrannical matriarch
She’s called a bitch.
I can’t think of a single word that is specific to the person you describe. Not everything can be narrowed down to a single word. But bitch is a good blanket term that covers this woman.
By the way, this question makes me think of the movie Throw Mama From The Train. I first saw it at the theater. That woman was so cringey that I walked out after 15-20 minutes.
wow, so fast and many!!! + I’ve got bonus - movie title to watch 
You’re right it’s a bitch/witch. The picture is ugly: bloody female viper with viper eggs around…
First word came to my mind “momsy”, but for English people it wouldn’t work - too affectionate term - same as “biddy”, thank you. Another word was “momster”, it’s closer but I’m afraid it can be too childish…
I like those you’ve suggested “a shrew”, “hag” and “reptilian tyrant”. I’ll keep it in mind
Thanka a lot!