I suggest working with supervisor-led topic ideas if you are trying to get publications with short timescale effort. Topic selection is a creative process which requires time and often leads to variable quality results as students are less aware of what has already been done in a field or how to do something well.
Cross sectional studies applying survey methodology and evidence based reviews are good topics and review and research studies that you can work on with your studen within such short period of time and get good results and learning experience.
Peter Samuels better go with choice of your supervisor. Usually supervisors have already some piece of work in their huge projects which could be also adjusted as master's level thesis. Three months isn't sufficient time period to plan and execute a good piece of research