How can i get custody of my grandaughter?

my daughter and her boyfriend are drug addicts. she has a two year old that i have been keeping 3-4 days a week since her birth. When the baby was a year old, my 77 year old stepfather began paying their bills because they were spending all their money on roxy's, xanax, and marijuana. He then let them move in his home. I told my mother and stepfather that they were on drugs and to please stop supporting their drug habit, but when i went there to stay to help my daughter get off drugs, I was kicked out because i confonted her and her boyfriend for stealing from my mother and stepfather. my parents treated me as if i were lying. my daughter and her boyfriend even had them convinced that it was me who was on drugs and stealing from them! They purchased a car for my daughter and she rolled the car over while arguing with her boyfriend and the baby was in the car! I told my parents and asked them not to buy them another one, but two weeks later they gave her another car. I found out that my daughter was having a ual relationship with her own half brother and my parents even allowed him to sleep with her in there home. Finally, my daughter, her boyfriend, and her half brother were all arrested for robbery, burglery, and dealing in stolen property. My parents have done nothing but cater to them and enable there drug addiction. the day my daughter was booked, they had her sign a four year custody agreement granting them full custody behind my back. She has always told me that she wanted me to take the baby because she was afraid that my stepfather was molesting the child. She said she felt cohersed into signing the papers so they would bail her out of jail. My mother is a pastor of a church and her husband's son is the sheriff in our county. Ironically the original social working investigating the case was replaced with my stepfather's buddy. They have told the case worker that I have mental problems and an alchoholic and that i grow marijuana. All lies! I can't afford an attorney to get my grandaughter, but I fear for her safety because my stepfather has never had any interest in any of the grandchildren except this one. My sister even had to give a baby up for adoption because they wouldn't help her. My family is very disfunctional and I don't have very much to do with any of them. My mother thinks she has every gift of the holy spirit and thinks she sees demons, fairies, and indian princesses. I don't want my grandchild to be raised in an environment like I was. I still suffer from my mother's mental abuse and suffer from depression. I only had one child and I lost her to drugs when she was fifteen. She hasn't been a part of my life because i refuse to cater to her habits. My little grandaughter is the only family i have left and they took her from me. They have spoiled her so much, she spits and scratches when she doesn't get what she wants. I don't think my stepfater is a child molester, but who knows, i just wander what his interest in her is when she isn't even his own blood and he doesn't even have relationships with his own grandchildren. My mother and daughter both know that the child healed my heart after i lost everything i had from being injured in a car wreck. Does anybody have any advise for me. I don't have the money or political pull that they have, but I can take care of my grandchild and give her a happy life full of love.