Send them home, reimburse them, Do the decent thing for once I think first year students who are in halls who are in quarantine and want to return home after that two weeks should be allowed to do so and refunded the hall fees.
Other than that, shut down the lives of 18-22 year olds for two or more years, absolutely nope. They don't want to sit in their parents houses watching life happening to someone else for another year or two.
It also shows why the vaccine won't be a solution for this age group. They won't receive it first, or even second, because they are not at huge risk of severe outcomes or death. We can't even roll out a flu vaccine quickly this autumn to over 50's, it's already not happening fast enough. The current statements about the covid vaccine are that it might make the illness milder rather than prevent it- what use will that be to young people who already mostly get an asymptomatic or a mild version?
I think carrying on some semblance of normal life for this age group is extremely important. Catastrophising and placing a whole cohort back in their parent's homes, unless individually they are very stressed, I don't think that's justified at the moment.