Elderly dad over medicated

Firstly I believe my mother to be a hypochondriac by proxy but that's a long & detailed story. My father's now in his late 70's & forced by my mother to constantly see doctors. They have a Physician's Assistant as a main provider but he also sees 3 specialists on a regular basis. They have him on steroidal asthma inhalers,diuretics,Statins,Blood pressure pills,heavy-duty-painkillers,benzos,antidepressant,mood stabilizer & she just prescribed an anti psychotic(he has no psych problems)because she said,"chronic pain causes the brain wiring to malfunction".
My dad broke down & cried saying his biggest wish is that he didn't have to see so many drs & take so many pills. The PA insists on seeing him at least 1 or 2x per month,weekly allergy shots,visits to foot dr,arthritis specialists,lung specialist & constant trips to the hospital for testing. It never ends.
The PA & my mom conspire behind his back & my mom insists it's the "best thing to do". I disagree. I'm watching my father literally being destroyed by these medications. What really slays me is a drs 'mistake' killed my maternal grandmother at age 58. He prescribed incredibly high doses of Methotrexate which led to ruining her immune system then led to nosocomial pneumonia. That 'specialist' then FLED back to his native country of Columbia but Gramma's ICU nurse told my mother, that outrageous over dosing of the Methotrexate is what killed her mother.
We could have saved her life if we just would have payed attention to the 'care' she was receiving. So. my mother places medical provider's on pedestals, thinks they're healing gods & trusts them 100%. Never mind that the American medical system's, the #1 killer of Americans... It's killing me watching this travesty take place & not being able to stop it. She argues with me no matter what proof, I give her that taking all of these medications is bad news.
I live with immense guilt every day because of not monitoring my grandmother's doctors, closely. HOW can I help my parents? How can I make my mother see that this is a big CAUSE of my dad's "health problems" and not the answer to the problems? Seems my mom thinks that the pharmaceutical companies know best. I could literally write a book of the many various accounts of harm(that I've witnessed)caused by the US medical system & pharmaceutical system but Gary Null already did that decades ago.
I love my parents and want them to live, a long healthy life. My mom's a good hearted woman, great mom & wife except for her unshakable faith in the US medical system. How can I open her eyes when the killing of her own mother didn't open them? I feel like taking that huge shelf of pills and destroying them. Sorry so long & detailed but I can't even sleep for the worry. It's my duty to protect my parents but...how? Thank-you for reading.