Halloween's rescue and vet care

Halloween is a cat who lives in my neighborhood. Last week, she became scared and took shelter high in a tree. Now, she can't get down. She has stayed there throughout thunderstorms and excessive heat and by the sound of her cries, she is becoming weak. Tomorrow morning, we have a climber coming to rescue her, but it will be pricey. Her rescue will cost $250 and she will need veterinary care to ensure that she has not suffered any health issues because of this. Her owner loves her very much, but cannot afford these costs, so we are looking for some extra help for this sweet, scared, baby girl. Please help if you can.