As you can tell, the answer is not clear cut.
But to make it simple: she is probably safe in not filing a MD return, since she was in FL for 11+ months and does not intend to return to MD.
Note that you can not claim her as a dependent. There are two types of dependents, "Qualifying Children"(QC) and standard ("Qualifying Relative"[QR] in IRS parlance even though they don't have to actually be related). You cannot claim her as a QC because she did not live you. You cannot claim her as a QR because she made too much money.
