As you only attended college full time for only four months, and had more than $4200 of income, you do not qualify as your Mom's dependent.
The requirement is for parts of 5 months, as a full time student. So, what was the exact last day the school was in session (not necessarily your last day of class). If it was May 1 or later, you meet the 5 month rule.
There are two types of dependents, "Qualifying Children"(QC) and standard ("Qualifying Relative" in IRS parlance even though they don't have to actually be related). There is no income limit for a QC but there is an age limit, student status, a relationship test and residence test. Only a QC qualifies a taxpayer for the Earned Income Credit.
A child of a taxpayer can still be a “Qualifying Child” (QC) dependent, regardless of his/her income, if:
- He is under age 19, or under 24 if a full time student for at least 5 months of the year, or is totally & permanently disabled
- He did not provide more than 1/2 his own support. Scholarships are considered third party support and not as support provided by the student.
- He lived with the parent (including temporary absences such as away at school) for more than half the year
