Question

how did helen learn the meaning of abstract idea

Answer 1

Well, I have always admired the deaf/blind people I encounter as an interpreter. There are people who were born both deaf and blind who achieve higher educations and work as professionals. you might want to contact a place like the Helen Keller Center which works with Deaf/blind people and see if you can get more information on this topic. Maybe you could even interview some Deaf/blind people. The technology today is incredibile, and so many Deaf/blind people use the computer and read email on computers equipped with refreshable braille displays. 
Deaf/blind people are truly amazing in what they do accomplish - especially those who were born that way.