Is it obligatory to fulfill a vow, parts of which were uttered aloud and parts silently? And does the absence of a specified duration for the vow affect its obligation? And can a mother annul a vow made by her daughter?

If you uttered a vow under the influence of obsessive whisperings (waswasah), then your vow is not valid, because one who is affected by waswasah is in the same category as one who is coerced. And if you doubt whether you uttered the vow, the 기본 principle is that it was not uttered and therefore not valid. As long as the matter is merely doubts, nothing is binding upon you. Turn away from these obsessive whisperings and pay no attention to them.