Moris, dressed in a wedding gown designed by British designer and Assange supporter Dame Vivienne Westwood, arrived at the prison with her sons and Assange's father Richard and brother Gabriel.
The extradition case of WikiLeaks founder Julian Assange, wanted in the US over the alleged leak of classified documents related to the wars in Iraq and Afghanistan, was sent to UK Home Secretary Priti Patel on Wednesday.
The 50-year-old's lawyers had argued that he should not be taken to the US because of a real and 'oppressive' risk of suicide and won the right to appeal in Britain's highest court.
Assange, 50, is wanted in the US over the publication of thousands of classified military and diplomatic documents in 2010 and 2011. The charges carry a maximum sentence of 175 years in prison.
Assange is wanted in the US on the charges of conspiring with Chelsea Manning, an American activist and whistleblower, to commit computer intrusion into the Department of Defence network to steal classified documents, namely Afghan and Iraq war logs and secret Department of State cables.