Are daughters a shield from the Fire for their father only, or is the mother a partner in this reward?

The hadith is general for both father and mother, stating that whoever has two daughters and treats them well, they will be a shield for him from the Fire. This also applies to sisters, paternal aunts, and maternal aunts. Treating them well is a cause for great reward and protection from the Fire, and this is specific to Muslims.

There are other deeds by which a Muslim enters Paradise and is saved from the Fire, such as one for whom three of his young children died before reaching the age of accountability, they will be a veil for him from the Fire. Likewise, whoever loses a beloved one from among the people of this world and endures patiently and seeks reward from Allah, his reward is nothing less than Paradise. This includes parents and all other relatives and friends if they endure patiently and seek reward from Allah, while also ensuring freedom from dying upon major sins.