Both my parents passed within a year of each other back in 1994-95 and i was devasted for quite some time.  It took my father  years before he came to see me and when he did i felt some inner peace, but my mother has yet to visit me in my dreams.  Can anyone explain maybe why?  I think she passed away angry at me for some reason....

Some times I feel progress is hindered, when we do not acknowledge some things in life, after all, we are here to learn.

Maybe at the time of your father's visit, you had at least acknowledged some things or accepted some things, which in turn meant you had learned from it, and progress was made in that respect.

However with your mother, you said she was angry at you for some reason, if you don't know what that is, then maybe it was something she felt you should have done/chose in this life, and you didn't.

How about sitting down at a quiet room and talk to your mother out loud, tell her of your times together, how much you miss/love her (?) and ask for personal differences/opinions/feelings to be put aside.  You respect her views and want her to respect yours too.  maybe that will bring out a closure between you both and she might then relent and come to visit?

JJ