It's highly unlikely that the qualifying relative rules apply. Since you worked Sep-Dec, you probably made more than $4150.
But there is no income test for a qualifying child. Yours is a common question. The answer almost always comes down to: did you provide more than half your own support for 2018. The support value of the home your parent provided is the fair market rental value of the home plus utilities & other expenses divided by the number of occupants. Scholarships are treated as third party support and is not considered to be support you provided. IRS Publication 501 on page 20 has a worksheet that can be used to help with the support calculation. See: http://www.irs.gov/pub/irs-pdf/p501.pdf
Since you were a full-time student for five months in 2018, he may qualify to claim you as a dependent. If he meets the requirements under either set of rules below, then he should claim you as a dependent.
Qualifying Child Requirements: