How can I get guardianship from my Mother who is not making the right choices for my Father?

My mother has been seeing a doctor for mental conditions for many years. But the past five years her actions were extremely dangerous to my father. Last year she had a tumor removed from brain.
These are just the following things she has done.
1.Gotten my fathers meds from VA, Family Doctor, Dementia Doctor and had my father on all doctors meds without telling the other doctors what he was on already.
She was smart enough to go to Publix, Walmart, CVS, and VA for all the different drugs. I then help my father get VA Support which was great because then he was able to get care at an assisted living facility. This took time but it was a blessing.
2. He got so sick from all the drugs that he was in Hospice. She told me to face it that my father was dying. I didn't believe that for one minute.
I have two other sisters who thought that I should bud out of my mother and fathers life. That mom knew what she is doing. Then she had a lawyer draw up Guardianship papers for my dad.
3. I saw my mother was shopping and spending money foolishly. She brought back a nearly new car to the dealership that was under my fathers and mothers name and brought a car under her name only.
4. After my father got out of hospice he went to a Rehab for nearly a year. While he was there my mother did not want me taking him out to lunch or anyplace else. Which I found weird. After a year there they told him he needed to go to an assisted living place.
5. When he moved in there. I had all the opportunity to take him out and she had no control. We went to the gym out to eat and to the stores I would go to. Just to have him hang out with me. He also gave up his walker and was doing just fine. Until one week me and my family went on a cruise and came back and my father looked terrible. His eyes were twitching and leg was shaking and I was freaking out. What happened to my father? They said my mother took him home the week I was gone and must of given him some of the meds she had at home. He was wearing clothes from Goodwill and oversized house slippers. I told the worker that the shoes were way too big and she agreed but told me my mother wants him to use them for his feet. Next day he fell and broke his hip and had to get surgery.
After he recovered my mother put him in a lock up unit and told the place she didn't want anyone visiting him. She had a restraining order for me not to see my father and that broke my heart. For over a year I didn't get to visit my father. She told people and neighbors that my father was so bad that he wouldn't know who they were if they tried to visit. Now I knew something was wrong. To make a long story short my mother had a brain tumor and had it removed last year. And she is still recovering and not doing any of my fathers payments or anything. My sister is sending the payments. They don't help me with anything and I am the one here with my father doing things all the time. They tell me to stop taking him out to eat that the ALF covers food.
6. My father gets $100.00 a month to spend on going out to eat with ALF. And that is because I put my foot down. My father should gets whatever he wants. He has worked all his life and supported my mother and family for him to be a such a tight rope. Mostly all his clothes are from Goodwill and the others are so old. I feel bad for him.
7. I have all the documents showing all the wrongful things my mother has done and all the meds she was taking out of all the different pharmacies.
8. Now my dad is moving to a better ALF. And I want to know how I can get either dual guardianship or full guardianship of my father. He also wants me to have it because my mother doesn't want him in his own home to visit at all while she is getting care from my sister over a year already. She also doesn't want me to use her car to take him anywhere and he tells me to take it anyway because he is more comfortable in it. My sister does not want to ask the doctor for a letter saying that she can't handle my fathers guardianship. Yet thinks that if anything happened to my mother she is clearly taking over the guardianship. When she doesn't even see my father maybe 3 times a year because she lives up north. It kills me to see that siblings only come into the picture when money is involved. She has been asking the where about of the deed to the house. Why? They already have a Trust done years ago. That I hope no one has plans changing anything on it. Because that was when they were in their right minds.

If anyone has anything they can help me with. I can't afford an attorney.
I Thank God for everything and to this day my father is without a walker and dancing and singing and has an active life. Thanks to God helping me and guiding me what is the best for my dad. And never give up.
My mother is still recuperating from the cancer she has and doing Chemo. But still angry because she is not doing better then dad.