My Puppy Was Bleeding From Mouth And Nose And Then Died What Would Be The Cause?

I'm so sorry you lost your dog.  
It sounds like she had internal bleeding from injury of some sort ~ maybe she had been hit by a car. To know for sure, a vet could do an autopsy and tell you the likely cause of death, but it would cost.
It might be better for you to try and think only of the happy times you spend with her, and hold those thoughts close to your heart.
Again ~ sorry for your loss.

Usually when puppies/dogs have bled out of their nose and mouth prior to dying, this usually means that they had some sort of head trauma. My great dane did the same thing. Maybe someone ran over the dog or it had a brain tumor or aneurysm. My vet for my dog told me the same thing.

No, it sounds as if your dog suffered a brain haemorrhage .

I had four kittens that died like that because the mother cat either laid on them and suffocated them or she shook them around.  Don't always expect it to be internal, watch out for the animals around the puppies too

My dog had a golf ball sized on her stomach what could that be?