I find it remarkable that Ellen and Susan made it back to England at all. Where, one wonders, did she get the money for the fares? Very few people returned, compared to the number who came.
I presume her father must have paid for the ticket as it doesn't seem that Edgar would have. To me, this suggests she was destitute and/or desperate to leave. The absence of the 2 children suggests death was more likely than desertion, although desertion was certainly not all that unusual. A deserter husband might show up in another province, further west, or in the US, as those were the usual directions in which they would move. (One of mine, from Ontario, went to Manitoba and married there and became a "respectable citizen" with a glowing obit while his wife was living in Ontario with her parents, not divorced. His first wife outlived him. )
Children likely in unmarked grave, possibly not recorded, but could be in burial records for the cemetery in question. Try local funeral homes for names of cemetery contacts if you can't find them elsewhere. Often, for the rural cemeteries, the burial records are held by local individuals and may go back a long way.
Littlewood cemetery seems the most likely. You could ask the library for a look-up, but may not find anyone listed if no marker. I would then try the Harris Funeral Home in London, Ontario for a contact person who would have the burial records, as they are in the north end of the city, closest to Ilderton.
info@harrisfuneralhome.ca
