The degree was conferred in 2014, the thesis, “The Changing Social Structures and Functions of the Family: The Case of Children’s Homes in Zimbabwe”, was apparently not available online until January 2018. According to NewsdzeZimbabwe, the thesis was published under her maiden name (Grace Ntombizodwa Marufu) on the UZ web site. Indeed, there is an entry on the library page of the UZ for Ntombizodwa G. Marufu, but no link to a PDF. Google finds a link, but the server does not respond. However, the table of contents can be found in a number of places, and the thesis itself appears to have been deposited at scribd in January 2018.
Update: The Zimbabwe Independent calls the thesis a fraud.
"Social Commentator Maxwell Saungweme described Grace’s PhD as the biggest academic fraud of the century.I can't find any citations from 2016 or 2017 in the version I found online, however. Interesting is Chapter 5 (p. 153): "Grace Mugabe Children’s Home was singled out as a model." This is a home the author runs herself. She does mention this a few pages later (p. 155): "I carried out this study when I was owner and founder of Grace Mugabe Children’s Home."
“It’s not a PhD thesis but a mere compilation of plagiarised text and quotations from grey literature, newspaper articles, television and radio programmes. It does not contribute original ideas to knowledge. It also cites prominently very old sources such as 1978 and 1985 works. A lot of scientific reviews have been done to this literature, and academic work must cite recent scientific journals and books,” Saungweme said. [...] Political analyst Pedzisai Ruhanya, commenting on social media, criticised Grace’s PhD thesis and questioned why there are citations from the years 2016 and 2017 yet, scandalously, Grace graduated in 2014."