I would like help with writing a thesis statement about my dad dying from cancer and how he handled the adversity.
First of all, you have my sympathy in losing your dad so young.
In this essay, please consider what your three body paragraphs will be about. Will you be discussing three adversities which he faced such as not being able to handle a full dose of chemo so that he had to go more often? Would one paragraph be about how he talked with the family about his death, allowing you to talk with him about goodbyes or things you would miss having him not be there? Would one paragraph be about the effect on the family of having a father with cancer or would you focus on only him?
Each of the questions I've included are to help you focus your essay so that your thesis statement contained in the introductory paragraph will introduce the reader to the three ideas you plan to discuss in your essay. For example, your thesis statement could be something like, 'My father, the center of our family, was diagnosed with cancer which forced him to face the effects of chemo on his body, affected the rest of the family in positive or negative ways, and because he could face his death and discuss it, so also could the family talk with him about saying goodbye.'
Just be sure that whatever you choose for your three body paragraphs, that the thesis statement introduces the reader to what you will discuss. Good luck on a difficult essay topic.
It seems to me that your essay would be most effective if you wrote about your own feelings about your father's death. Otherwise it could seem too detached, too clinical, too objective. I suspect that you want to write such an essay because you would like to express your own feelings, even including your feelings about the way your father coped with suffering and dying. If I am correct, then it would seem that your thesis statement should show clearly that you intend to write about your father's death from cancer and how you felt about the momentous event as well as how you feel about it now, afterward. It sounds as if you feel proud of your father because he was able to face his tragedy so courageously. Something along those lines would make a good conclusion--and perhaps also a good introductory thesis statement.
I am reminded of three works about the subject of death and dying. One is the book On Death and Dying by Elizabeth Kubler-Ross. Another is Dylan Thomas's famous poem about the death of his father titled "Do not go gentle into that good night." A third is Leo Tolstoy's long story "The Death of Ivan Ilyich." If you look at these they may help you to get at the feelings which you may be holding back.