Handicapped pre-school child school laws?

We have a 3 year old granddaughter who is severely disabled. She began attending a public school (small rural area) last fall. I would like to know what options are available - does she have to attend the public school system (her mother receives istance for her and is a single mom) Does she have to attend school at all? We have issues with the (very young) teacher that we feel shows lack of knowledge with a child as handicapped as my granddaughter (only child with both physical and mental issues - 75% of brain destroyed due to stroke at 2 weeks of age). There have been issues with her wheelchair being broken - in which they denied and tried to blame us....she has issued complaints because she claimed my granddaughters hair was not combed - without taking into consideration that my granddaughter's head is full of "hills and valleys" due to surgeries and tubing in her skull and her poor hair will not lay down - it also breaks off due to her twisting and turning her head against the wheelchair back. Another complaint was her teeth are crooked and her breath foul...again without considering that she sits with saliva in her mouth continually and her physical disability has everything on her body crooked...it is just becoming a bit ridiculous. We were wondering what other school options may be available - in our rural county the public school system is the only option here but there must be more than this - somewhere. The "system" will not send the therapists to her home since she turned 3 years old and told us the public school was our only option from here out....that cannot be right. I am at a point where I do not want her there any longer. Also - there is a dress code...she can wear any SOLID color polo shirt (or on up) but slacks (blue, black or Kaki) or jeans must be plain without ruffles, flower designs, pockets etc...she wears 18 month pant sizes and 24 month shirt sizes - infant sizes and everything has ruffles and flowers ...and impossible to find the requirements...the school advised us to try Coles or Penny's!!! My daughter cannot afford much being a single mom.