I need to get out my girlfriend out of her abusive house

Me and my girlfriend are both adults. I am 20yrs old and she is 18 we both in love and want to be get married after completing studies or attained marriagble age. My families is ready to support me in all aspects. Her parents got knew about our relationship and they threatens to marry their relative forcefully without her consent and intention. Her parents are too abusive from her childhood and now its got harder. Since they knew about our relationship they beat her up and tortures her.My family is ready to accept her and took up all her expenses till we get married. What is the procedure to leave her home or the ways that she could get out of her home. Her parents will definetly disturb us once she get eloped with me such as lodge complaint against us. What can we do to get her out from her home safely. Any ways will be ok such as lodging first complaint or using live in relationship as a sheild till we get married... We need a clear idea for proceeding further more