Daughter 21 and graduated college. Husband wants to cut support. She has no job and home and I have more expenses. can he do this

Yes - he can because if she was not in college - if she had dropped out for example - then he would have been able to stop support.  He needs to file an application for emancipation, but yes, support stops.  It really only continues beyond age 18 because the child is in college.  Therefore if she is not, for whatever reason, support ends.