My eight month old niece already knows how to stand on her own and can walk when being guided. Her parents does not prefer to let her use a walker. Is there a safe alternative on teaching a toddler to walk?

Practice makes perfect, this is key for your niece when she is at this stage. The more she is use to standing and being on her feet the more likely she will feel comfortable to take those first few steps. Give her also the most loving appreciation and caring motivations for her to develop her confidence and finally walk on her own .