I dreamed that my dead mother was still alive and always lost.

You have this dream because you miss your mother so much. This is what people often say: you miss your mother every day and dream at night. When you miss your mother during the day, your brain will reflect your subconscious at night.

I can see from your short sentence that you are a dutiful son. When your mother was alive, it was probably because you didn't take good care of her, so you felt guilty about your mother, but you couldn't come back from the dead, so don't blame yourself too much. Have a good life. As long as you are happy, your mother will bless you in heaven.