When a parent passes away remember that you have begun a new phase of birr (dutifulness) to that parent.
A deceased parent is in greater need of his/her children - even more than when they the parent was alive. What children do for the parents during the parent's lifetime is for the worldly needs.
But after death only Allah knows what good and bad is in store for the deceased in the grave.
Du'a - i.e., supplication to Allah - for rahmah (mercy), asking Allah to shower the deceased with His mercy is invaluable for the deceased.
Through the child's Du'a, Allah - with His grace and mercy - enlightens the grave removing the darkness and expands the grave thus removing the suffering. And Allah makes the grave a garden from the gardens of Paradise for the deceased.
Therefore, always remember your deceased parent/s, and always ask Allah to shower them with His mercy, enlighten their grave and expand it.
For example as you are about have a meal think about the many wonderful meals your mother had prepared for you and how she looked after you all your life. Your heart will surely soften and at that point, let it drive you to offer a similar meal to an orphan, widow, divorced or needy person on behalf of your deceased parent, begging of Allah to reward them for it. Give charity on their behalf, recalling the many favours they did for you.
Never forget parents. No matter how harsh they may have been with you, only Allah knows the love they had in their hearts for you.
Remember them in your Du'a during sujood - the prostration - between the adhaan - the call for prayer - and the iqamah - the in-masjid call for prayer just a minute before congregational prayer, and in every act of worship and at all times.
Give charity on their behalf privately, wipe away the tears of orphans, widows and divorced (through charity) on behalf of your parents, quench the thirst of the thirsty on their behalf (by having a well dug, for example).
Go out of your way to be the best child to your parents for they have sacrificed much to raise you.
This is the Du'a for parents:
*رَّبِّ ارْحَمْهُمَا كَمَا رَبَّيَانِي صَغِيرًا*
*Rabb-ir-ham-huma kama rabbayaani sagheera* {Quran surah 17, verse 24}
Translation :
'My Lord .. Bestow thy mercy on my parent/s as they cherished and raised me in my childhood'
Lastly let us teach our children about this Du'a for one day we all shall need it.
