Help for social phobia?

What can be done for adults who suffer?  When my daughter was a senior in high school, she went on meds.  This was the first time I learned that she was afraid of going to school her entire life.  She went off celexa after about 9 months because she developed other problems.  She developed coping techniques whenever she gave a speech.  Long story short, she finished college and had several job offers at the beginning of her senior year in college.  She accepted w/ a prestigious company and all was well for a few years.  She's now 29 and quit her job... Her phobia is worse and she prefers to stay at home.  Fortunately, her husband makes a good income.  I'm so afraid she'll become homebound now.  What can be done?  It's so hard for me to understand.  It seems like she's giving in to her phobia and not challenging herself.