Source: The Great Interpretation of Dreams (Ibn Sirin)
(By analogy with a vehicle and illness) An ambulance in a dream indicates imminent relief and salvation from hardship or illness.
Source: Perfuming Humanity in the Expression of Dreams (Al-Nabulsi)
(By analogy) An ambulance indicates a man who strives to fulfill people's needs.
Source: Signs in the Science of Expressions (Ibn Shaheen)
(By analogy) An ambulance is interpreted as relief. Whoever sees himself riding in one, God will relieve his worry.