Aprepitant- and Olanzapine- Containing Anti-emetic Regimens With High Dose Melphalan

The purpose of this study is to help answer the following research question: * Whether administration of an aprepitant containing regimen, an olanzapine containing regimen or regimen containing both will prevent nausea and vomiting better for patients undergoing an autologous stem cell transplant with melphalan chemotherapy. Both of these medications are approved by the United States Food and Drug Administration (FDA) for nausea and vomiting. * Participants will be randomly assigned to one of the 3 treatment groups: * Arm A: aprepitant containing anti-emetic therapy * Arm B: olanzapine containing anti-emetic therapy * Arm C: Aprepitant plus olanzapine containing anti-emetic therapy