unwanted guest

Recently I phoned a friend that I had in high school, many, many years ago. I just wanted to find out what she was doing. She lives several states away from me. We talked a little while on the phone, and I realized that she was a little "off", and we really had nothing in common any longer. She has called several times, and I have talked to her. Now she has informed me that she is coming to visit and will bring a friend. I am appalled at this thought. I really don't want to hurt her feelings, but I can't handle this. Should I just tell her that I don't want her to come, and tell her why, or just not answer her phone calls?