<human>: I have an excellent mother. She has always taught my sister and I to be independent and self-sufficient. This will be her first Mother's Day without either of us at home.  A couple years ago, my sister moved out to California while I stayed at home (in Arizona) to finish college. Now I've moved to Alabama for work.  After I left I noticed she seem bummed out when I would talk to her on the phone. My Dad has commented to me that she has been unusually moody since Christmas (the last time we were all together).  

I called her this afternoon just to chat, and I could tell she had been crying. After a little prying I got her to tell me what was wrong.  She told me that she basically feels useless since I left. Neither me or my sister need her anymore and she doesn't know what to do with herself.  

What can I do or say to help her? I know this is a phase many parents go through, but I've been gone nearly a year now and I don't like the idea of her being miserable.  Do you know of any good suggestions or advice I can give her? Thanks for any help.

Can you succinctly summarize the text in 1-3 sentences?
<bot>: Sister and I have moved away from home to opposite ends of the country. Mom is having a prolonged existential crisis. Need help/advice/suggestions!