How does the government, secrets, and the dream of freedom play and integral role in the death of Lennie in Of Mice and Men?
If you take into account the historical context of Of Mice and Men, I think you will find that it is a time when mental institutions were not traditionally humane to people with disabilities if at all. For example, in the 1930s, many patients diagnosed with or presumed to have schizophrenia would have been treated with insulin to induce shock and therefore a temporary coma. Today, to do that might be considered a violation of human rights. As a social program, a mental institution would be run by government dollars in many circumstances. Since Lennie would only be able to be funded this way, he would have suffered in one of these institutions had George decided to let him live.
George kept the big secret (and so did Slim as he knew) that Lennie had been in trouble for inappropriately touching a woman in their last line of work. This would have been important information for the boss to know considering Curley's wife's affinity with spending time with the men. This secret dies with Lennie and George, for all we know, continued to work at the ranch effectively for a long time. George also keeps a secret the circumstances of Lennie's death.
The dream of freedom took Lennie into his death as George described the little ranch they were going to have as they lived off the fatta the land. He painted the picture beautifully and let Lennie believe that there were many opportunities to raise the rabbits.