Encourage your friend to get professional help.  You may even be able to find one that will come to the house to help at first.  This is a serious condition, but is very treatable.  It is sad to see people suffer from this, when they can really be helped.  Maybe not cured, but at least they can get out and about.  I hope you can help.

I agree that you should try to get her to talk to you about it. You could even look up some stuff on the computer for her and see if there are any support groups online.

It really depends on what the apparent cause of this anxiety or fear is. It is probably most effective to tackle the source rather than find solutions for the effects. A good start would be to talk to her about it.