Was the daughter's action correct in preparing food for mourners from her deceased mother's money, and donating one-third of her money as ongoing charity to dig a well, based on the mother's will to prepare food for mourners and her will for ongoing charity?

If you agree to dedicate one-third of the wealth as an ongoing charity (Sadaqah Jariyah) for your mother, then this is a permissible act, and digging wells is among the best forms of ongoing charity. As for her bequest to prepare food for mourners, it is not obligatory to fulfill because it is an innovated practice (bid‘ah muhdathah). The Companions considered gathering for the family of the deceased and preparing food as a form of wailing (niyāḥah). Furthermore, a bequest involving disobedience (to Allah) is legally invalid and must not be carried out. If the bequest is invalid, then your voluntary act of establishing an endowment (waqf) for her from the inheritance is permissible, provided you all agree and there is no minor among you.