Do the math. Most years you get nothing for claiming yourself. For 2020, you will probably get the $1800 stimulus/rebate credit. But your Mom will miss out on the $500 dependent credit and the up to $2500 tuition credit.
Students under 24, who do not work, are not eligible for the refundable portion (up to $1000) of the tuition credit.
But, it's not optional who gets to claim you; the rules must be met. And, as your surmised it's most likely the support rule that will govern. Students away at school are still considered as residing with their parents (you are only temporarily away).
The support value of the home, provided by the parent, is the fair market rental value of the home plus utilities & other expenses divided by the number of occupants.
The IRS has a worksheet that can be used to help with the support calculation. See: http://apps.irs.gov/app/vita/content/globalmedia/teacher/worksheet_for_determining_support_4012.pdf
