As you must know, Machine Learning is one of the hottest areas of computer science. You would not go wrong to do an MS project in Machine Learning. The department offers at least two options. 

• Prof. Mohammad Pourhomayoun teaches a two-course sequence in machine learning: first data science; then neural nets. This is his area of specialization.

• I have recently become interested in a particular branch of machine learning known as reinforcement learning. It is the technique DeepMind used (a) to learn Atari games and then (b) to build AlphaGo, the world champion Go player. (AlphaGo Zero, the latest version, is even more powerful than the version of AlphaGo that beat the world champion!) This 6 1/2 minute video provides a short, simple example of one form of Reinforcement Learning. This video, by the same guy, is a slightly longer example. You can find many examples and discussions of Reinforcement Learning online. Some are more sophisticated and technical than others. There are many libraries available; you don't have to start from scratch.  The best is probably the Open AI system. I would be happy to work with students who want to do an MS project on Reinforcement Learning. If you are interested, let's talk about it.