What do I need to do to get temporary guardianship of my grandchild who has been living with me for the past ?

My grandson has been living with me since April 2010 and his mother is in another city. She currently does not have a home of her own. She has been living with different people for the last year and a half. Now he is at the point he needs to get ready for school and she can not come where I am because she can not get a ride over here. I have to get him to the doctor and get him into school.