I am sorry to hear about the loss of one of the kittens. It must be tough to see them in such a cold and thin state. It sounds like the two remaining kittens need your help and care.
To start, you can keep them warm by providing a heating pad or warm blanket. Be sure to monitor their temperature to avoid overheating. It’s also important to provide them with proper nutrition. Consult with a veterinarian or animal rescue organization to determine the best formula and feeding schedule for their age and condition.
It’s important to keep them clean and provide them with proper hygiene. Gently clean their eyes and ears with warm water and a soft cloth. Keep their litter box clean and provide them with fresh water.
Lastly, it’s important to monitor their health closely. If you notice any signs of illness or distress, seek medical attention immediately. With proper care and attention, these kittens have a chance to thrive and grow into healthy cats.