Did your Mom live to see your son? If not, maybe you're dream means you wish she'd been able to see him.
Then maybe you're subconsciously wishing you could share the happiness of having a child with her, sad that she didn't get to be with her grandson.
It means that you are worried about your mother dieing and something taking your son's spirit from him. Its just your subconscious worries being shown.
You just wish your mother was there to see your son. You aren't really sure if she's watching over, I guess your not sure that of type of thing. Don't be alarmed she's always watching over you and will always watch over your son.