Hey Derby....I can tell you from my own personal experiences on this issue, that the deceased can come to visit us in our dreams.
However, I think that I should also add, that they may not come to visit us at the specific time that we ask them for......they are in a different time frame there.
I have heard the phrase: a blink of the eye is like a thousand years.
I know that there are lots of people here on this forum who can accomplish getting things much faster than I can at this point.....if they want to connect with someone that night, they can......I haven't quite acheived that yet!
I was 8 years old when my mom died...and for the years that followed, I struggled with her death. Oh yes...I think I coined the phrase back then on 'missing someone'.....lol.....but I also had a tremendous amount of anger and disbelief to deal with. I thought she had just died because she didn't love me enough to get better....that she didn't want to stay here with me and just wanted to go and be with Jesus forever.
When I was expecting my first child (at age 20)....she came to me in a dream for the first time. We had an awesome visit....she sat on the couch and I sat on the floor in front of her and we talked about all the worldly changes that had occurred since she died and of all the changes that my dad had made in that house. At the end of that visit she gave me a big hug and told me that she loved me dearly and that she didn't leave because she just wanted too....she told me that she is with me all the time and that she loved our visit and she promised she would come back and visit again. Then she just kind of floated up to the ceiling and then vanished.
About 3 months later, she came back and gave me a handwritten message...I was trying to settle on a name for a girl and this one night, a hand appeared in my dream and I watched it write out the name that came to be the name that I gave my first child, a daughter. Years later, I learned that this name was my mom's favourite name and that she had wanted to have one more girl in her life so that she could name her this name.

My dad died in 1987....and on that night, I was in the shower. I didn't know at that time that he had passed. While showering, a sudden and very strong feeling came over me that someone was watching me.......it gave me the willies!! I covered up and got out of there.....

I couldn't shake this feeling.
About 20 minutes later, there was a knock at the door and it was a family member coming to give me the news that dad had died (we had no phone at that time)
My dad's spirit hung around with me until the night of his funeral service....and then he gave me a fianl goodbye. As I lay in bed, I felt his hand softly touch my cheek and in my head I heard his words: I love you.....love your children as if there is no tomorrow
I believe his heart was giving me a message that he was hurting from himself.....that he felt he never loved his children enough in this world....and his message was to not make the same mistake.
In all this babble, that I do so well.....

...yes, we do get visits from our loved ones in our dreams. It is the easiest way for them to communicate with us.
But don't despair if you don't get a visit right away.....sometimes it just takes awhile.....but it will happen.
I even think that a visit thru a dream might come at a point in our life when we most need their love and support.....as with my visit.
And something else Derby.....have you ever wondered why there is no saddness...suffering...pain....greiving in the afterlife? It's because they now know that there is no need to feel this way...they already know that they will see their loved ones again.....it's a fact. So there is no greiving over their passing.....only we feel those feelings and it is because we don't know what they know yet.
You will be with your mam again...and, your mam is with you now.