Question: In Buddhism, what are the best ways to express filial piety to our parents?
Answer: Beyond the usual ways of taking physical care of them, in terms of offering enough clothing, food, shelter and such, which are worldly in nature and thus still limited in duration of benefit, the ultimate spiritual way to be filial is to guide them to practise Nianfo (mindfulness of Amituofo; Amitabha Buddha), so as to be born in his Pure Land, where liberation from the cycle of birth and death is guaranteed.
The Buddha taught that there is no way to repay to profound kindness of our parents, than to share the Dharma with them. Since we are non-Buddhas, although we cannot share the Dharma with them perfectly, we can still share enough of the Pure Land teachings with them, to enable them to reach Pure Land, where they will definitely be able to master learning and practice of the Dharma through Amituofo.
Also, as the Pure Land Tradition’s 13th Patriarch Great Master Yinguang (净土宗十三祖印光大师) taught in ‘The Three Great Essentials When Approaching Death’ (临终三大要), ‘If you have fathers, mothers, brothers, sisters, and all relatives, with serious sicknesses, the conditions of which are difficult for full healing, you should give rise to the mind of filial piety, loving-kindness and compassion, to urge them to recite the name of Buddha [Amituofo] for seeking birth in his Western Pure Land, also offering support-chanting. Enabling dying persons to die thus, they can be immediately born in Pure Land. Of its benefits, how can they be named?’ (其有父母兄弟，及诸眷属，若得重病，势难痊癒者，宜发孝顺慈悲之心，劝彼念佛求生西方，并为助念。俾病者由此死已，即生净土。其为利益，何能名焉？)
Understanding Amituofo Via The Amitabha Sutra
Destination Pureland: How To Have The Best Rebirth
The Three Great Essentials When Approaching Death
What Basic Integrity & Gratitude Should We Have?