My Aunt is on Medicaid. She has a little money in a 401k. I need to save some in the event of her death. How do I do this?

Depending on the state, she may be permitted to have an irrevocable burial account set up with the funeral home of choice. You need to check to see if this is permissible under your state's Medicaid plan, and make sure that it is "irrevocable". Under no circumstances, hide any assets. The truth will come out.