Probably not. The requirements for claiming children between the ages of 19 and 24 who are students are quite a bit less restrictive than the rules for claiming adults who are not students.
If you were not a qualifying student, the following must apply:
To be a student, they must be, during some part of each of any 5 calendar months of the year:
A full-time student at a school that has a regular teaching staff, course of study, and a regularly enrolled student body at the school, or
A student taking a full-time, on-farm training course given by a school described in (1), or by a state, county, or local government agency.
The 5 calendar months don't have to be consecutive.
Since you were not a student, your mother would only be able to claim you as a dependent under the qualifying relative rules. Those rules are as follows:
You need to be related or a member of the household (living with her) for the entire year. As her son, you meet this requirement even if you did not live with her for the entire year.
Your income cannot be more than the exemption amount of 4,050 for 2016.
Your mother must have provided more than half of your support. The support test result is best determined by filling out worksheet 2 on page 16 of IRS Publication 501
