Quoting advice from others in a paper
If the paper has been already accepted, I am not sure that you are even allowed to add co-authors at this stage. So, the only option that you have is to mention his/her contribution in the acknowledgment (e.g., "I am grateful to XYZ for his/her help on data analysis"). Anyway, if I understood you correctly, the help was limited to 3 hours consultation. For such contribution a person usually will not expect to be part of the paper (unless you promised this explicitly).