It is forbidden to curse a parent, even posthumously.
Daily Mitzvah (Rambam)
Day 330: Negative Commandment 318, 319; Positive Commandment 210, 211
Negative Commandment 318 (Digest)
Cursing a Parent
Negative Commandment 319 (Digest)
Hitting a Parent
It is forbidden to hit a parent.
Positive Commandment 210 (Digest)
Honoring Parents
"Honor your father and your mother"—Exodus 20:12.
We are commanded to honor our parents. This mitzvah includes serving them food and drink, and helping them dress and go.
Positive Commandment 211 (Digest)
Revering Parents
"Every man shall revere his mother and father"—Leviticus 19:3.
We are commanded to revere our parents; our consideration of them should be as we consider an individual whom we fear, who is able to administer punishment, such as a king.
This mitzvah includes not sitting in a place reserved for them, not voicing an opinion in their presence, and not contradicting them.
From "Sefer Hamitzvot in English," published by Sichos in English.