Based on the text, what is the ultimate goal known as Moksha, and what is the sole method for achieving it?

The ultimate goal, as defined in Chapter 50, is Moksha, or liberation. This is not a place or an external reward but is simply "abiding in one's own form." The text is very clear that there is no other form of liberation besides this. The sole method for achieving this state is through the removal of ignorance (Avidya) and the causal body it creates. This removal is not possible through any other means except for one specific realization: the knowledge of the unity of Brahman and the Soul. Only when this knowledge occurs can ignorance be dispelled, allowing one to abide in their true form, which is Moksha.