Our parents have sacrificed so much to raise us. We can never repay them for their kindness. However, we can do our best to honour them and treat them well.
Allah s.w.t. says in the Quran:
Your Lord has decreed that you worship none but Him and that you be kind to parents. Whether one or both of them attain old age in your life, say not to them a word of contempt, nor repel them, but address them in terms of honour
(Surah Al-Isra, 17:23)
One of the best things that you can do is to constantly make sincere dua for them, even if they are no longer with us. The Prophet s.a.w. encouraged us to keep praying for our parents. Indeed, prayers will continue to benefit them.