Yes, as a U.S. Citizen (assuming you are over 21 years of age), you can petition your parents. It will be an immediate relative petition and will go much faster than the petition from your grandmother to your parents.
Brian D. Lerner
If you are a U.S. citizen, you can confer permanent resident status on your parents if and only if you are over the age of 21 and your parents are admissible. You should discuss the petition process and the immigration process with your attorney.