After losing someone in your life (death), did you dream about them a lot after their passing? Were they sick/dying in your dream? Do you think that you're dreaming these things because you're trying to come to terms with their passing?
I know this isn’t quite relevant, but I have a lot of dreams where someone who is still living irl has died, and I wake up afraid that that person really did die. My theory about your dreams is that thoughts of your mother are still very prevalent, so she appears in your dreams. Perhaps your feelings are unresolved, you haven’t reached some kind of closure.