Dreams involving loss of memory, fear, and a childlike mental state can be quite distressing and often reflect deeper emotional or psychological concerns. Here are some interpretations of the key elements in your dream:

1. Losing Memory: This may symbolize feelings of insecurity or anxiety about your identity and the future. It could suggest a fear of losing control over your life or your sense of self.
2. Childlike State: Reverting to a childlike mentality might indicate a desire to escape adult responsibilities or a longing for the safety and simplicity of childhood. It could also reflect vulnerability and the need for support during challenging times.
3. Stairs: Stairs often represent challenges or transitions in life. Your fear of falling down the stairs may indicate apprehension about facing these challenges or moving forward in life.
4. Family Dynamics: Your interactions with your sister and mother reflect the support system around you. Their concern suggests that you may feel overwhelmed and need assistance or understanding from those close to you.
5. Water on the Floor: Water can symbolize emotions and the subconscious. The act of cleaning with water, especially in a way that makes you feel stressed, may represent attempts to manage or cleanse emotional turmoil in your life.
6. Inviting Someone for Support: The presence of the guy you’ve been talking to may signify a desire for connection and support. His ability to understand your situation could reflect your need for empathy and comfort during difficult times.
7. Prayers and Support: The image of family praying reflects hope and a desire for healing or resolution. This suggests that you may be seeking help or guidance in your waking life.

Overall, this dream might be urging you to confront feelings of insecurity, seek support from loved ones, and acknowledge any emotional struggles you may be facing. It could also be a reminder to take care of your mental health and reach out for help when needed. Consider reflecting on current life challenges and whether you're feeling overwhelmed or in need of support.