sowhatnow - sounds like your mother, and probably you, experienced sleep paralysis. It's a pretty well understood phenomena that is probably responsible for a pretty significant number of so-called supernatural experiences. In short, your body is either gearing up for sleep, or not yet fully out of sleep mode (in the evening or early morning respectively) and the body is still paralyzed and the visual centers of the brain are still highly active. Your body is usually partially or fully paralyzed when your asleep (that's how you keep from running around the house when you have a dream about being chased) and sometimes this can start to take hold a bit before you fall asleep. you probably inherited a predisposition for the condition from your mother.
When you're falling asleep, your brain is also gearing up for some wild, crazy and realistic visual and auditory hallucinations. Most folks call them dreams. Just like the effects that keep you paralyzed in sleep, this can sometimes start a little bit earlier or last a little longer than needed causing waking hallucinations.
Effects like this also explain why some families seem to be haunted, with many generations reporting similar visions in the moments just prior or just after sleep.