My wife is getting cited with failure to comply with "Duty upon striking an unattended vehicle" because she scratched another car in the parking lot and left without doing anything, according to a witness. The police said that we will have to go to court and since its not anything major we will receive a fine. Does anyone have experience with situation like this and what impact it might have on the GC process and filing the I 485 section about citations etc. Stressing out a lot. Thank you all in advance.

You should be fine no need to stress. You will need to, however, submit the court documents and final deposition letter.

Only COMTD(crime of moral turpitude) bars an applicant for changing status. COMPTD can include things like theft, prostitution, battery etc.

Talk to your GC lawyer too ...

No, it shouldn't be a concern. Misdemeanor doesn't affect the GC or even your usual employer background check etc. It is more worry if you get into committing more serious issues that are considered a felony.