Looking at the entries, it seems that there is a confusion of informations. My understanding is: Catherine Jane [nee Moore] Wallis was the Matron; and Miss Catherine Walsh was a stewardess. She is not listed on this site.
The address [57 Church Road] given on this web-site for Mrs/Miss Richard James Wallis [Katherine Jane Moore] is the one listed in the US Senate Crew list as being the address of Miss Walsh. Mrs Wallis' address is given as 23 St Marys Street.
So was I after I read the two Wallis entries. I believe that the best thing is to ignore them and accept as per other Crew Lists: Miss Walsh and Mrs Wallis. So two stewardesses: Mrs Snape and Miss Walsh; and Titanic's Matron, Mrs Wallis died.