If you can find death certificates for these two then you should have some names and occupations of their parents to go on. Assuming the details are filled in!
I've had a wee look on Scotlandspeople and there's only one Mary Ann Miller, with another surname of McAusland who died aged 43 in Falkirk, Stirlingshire in 1876.
Likewise there's only one Peter McAusland born abt 1833 who died in the same location as above in 1877 aged 44.
It looks a pretty good bet that these are you're folks.