That sounds like a psychological issue, did you see a therapist after your mom died?
You should, even if you think you are fine you probably have some problems you never dealt with. I know im only 14 but my family has dealt with a lot of psychologists and it really helps believe me
i read some where that we should try write down the dream in detail...as soon as we get up...if its reoccurring..u might find some links . i'm having the same dream of my mom who passed away 4 yrs back she keeps coming back to life in my dreams.... don't know y i'm seeing such a dream.?...but still looking for an answer..... i will try and do the same thing to find out if she wants to say some thing to me or not.....hope it helps you too
Ask a Medium some are their to help and if they get you need it and can not pay they will do it for you!
see a pyschic. she is trying to tell you something. Is she leaving other signs?? Keep an eye out for more signs :)
Is the dream at a significant time of year. it could be anxiety and it playing on your mind before you go to sleep. or it could be much deeper it would depend on how much you believe.
the dream if proberly caused due you knowing its the anniversary and subconsiously upset with the mannor in which she passed. may she rest in peace and hope you feel better. there is a long science type explination for this behaviour.