What do you do when you find out they are not taking blood pressure pills prescribed 6 months ago? Now a big fall? Found out by being at dr?

Maybe she just cannot swallow pills.

You first of all identify what the problem is, i.e. find out why your mother wasn't taking her prescribed medication. Then you see what you can do to put that right.

Does she object to it?
Does she forget about it?
Does she not know how to order it?
Is she taking so many tablets she gets in a muddle about them?
Will she allow you to assist with her medications?

Hopping up and down on the spot and tearing your hair out, although it is a natural reaction, is not going to help anyone. What has the doctor had to say about it?

Do you know why they aren't taking the pills, is it stubbornness or forgetfulness?
If it's an inability to remember then having a pill organizer may help - some are high tech and have reminders.