Additional Study Information: There are two main types of stomach cancer based on the appearance under the microscope: intestinal-type and diffuse-type. Some stomach cancers also have a mix of intestinal-type and diffuse-type (mixed type). You are being invited to take part in this research study because you have been diagnosed with stomach cancer that has spread to other parts of the body and/or cannot be surgically removed, has diffuse-type or mixed-type cells or has gene alterations that are associated with diffuse-type stomach cancers (such as mutations in the genes CDH1 or RHOA), and you have already been treated with chemotherapy and your disease is now growing. The purpose of this study is to determine if the combination study treatment with defactinib and avutometinib is effective in improving the length of time after the start of treatment in which a participant is alive and their cancer does not grow or spread. Avutometinib and defactinib have been studied in patients with other tumor types such as low-grade serous ovarian cancer, but they have not specifically been studied in patients with stomach cancer. Please note that defactinib andavutometinib are investigational drugs. This means that the drugs have not been approved by the Food and Drug Administration (FDA) for medical use in participants.