Can a mother be helped and guided regarding her daughter's condition, who suffers from an enzyme deficiency in the blood after a series of health problems, especially since doctors have stated that there is no cure for this disease and that these children live for no more than two years?

What the doctors have said is not definitive; they cannot rule on a future matter except by conjecture and effort, and there is no disease without a cure. You have done well by supplicating, reciting the Quran, and observing hijab, for the acceptance of supplication and Allah's pleasure are attained through obedience to Him and drawing near to Him. Whatever Allah decrees for this girl will be good for you in any case; for the affair of the believer is all good: if he is afflicted with ease, he gives thanks, and if he is afflicted with hardship, he perseveres.