The major features of Virginia Henderson's "Nursing Need Theory" and Shirley M. Moore and Cornelia M. Ruland's middlerange "the Peaceful End of Life Theory" (PEL Theory) are focused in this paper. They are grand nursing theories designed for nursing practice, research, and education. These theories were derived in part from the general system, process, and outcomes theory, which is based on the Donabedian structure model. These ideas are primarily concerned with the treatment of terminally ill or dying patients and how to keep them comfortable and at ease. The four assumptions in this context are health, personhood, environment, and nursing. These theories help deal with critical situations. The "Nursing Need Idea" by Virginia Henderson is an influential theory that has had a lot of influence in the nursing sector. This enormous theory is a big theory of human needs that focuses on empowering patients to be as self-sufficient as possible to obtain the best possible outcome at discharge. Henderson's nursing model elaborates on the nurse's job, emphasizing the need to assist patients in rehabilitation and ensure their basic needs are met. If the patient's ailment is terminal, they will be shifted to life support. Middle-range theories have their importance in nursing research, and they are much more feasible to practice than grand nursing theories. Middle-range theories can describe, explain, or forecast phenomena while also being testable.