Is it permissible to divide the amount vowed for a mosque into two parts? And is it valid to pay the price of a Mus'haf in cash to mosques instead of buying and presenting the Mus'haf itself?

Whoever makes a vow to obey Allah, it is obligatory for him to fulfill his vow. He must give the vowed amount to the mosque in one lump sum if possible, otherwise, in installments according to his ability. If the decision to buy a Quran for the mosques was a vow, then it must be fulfilled unless the mosques no longer need a Quran. However, if it was merely an intention or a determination, then it is not a vow, and you are obligated to fulfill it, but you can pay the value of the Quran instead.