Marion does not jump out at me in the 1881 census. She may, however, be on her own by that time and therefore is not obvious.
If John is alive in 1861 and is dead by the time Marion dies in 1886, then a look for him between these dates is the way to go, initially, I would think.
I looked for a John Hogg between these 2 dates and used the ages 44 - 81(adding on a few years either side of the age he should be) and searched East Lothian only. There were 5 hits. No credits left so could not look further. Perhaps a look at these 5 would be a start. You may have already looked at these last night.
After that I am stumped
Perhaps someone else more experienced than I can take you further.
Good luck
Jean