Hello Molly,
Found a transcription of the 1871 Census but the original must be difficult to read. No surname for Ann's son-in-law and family.
1871 Census. 176 South St, Perth.
George -- 30 Shoemaker.
Jane -- 34
Helen -- 9
Mary Ann -- 5
Jane -- 3
Jessie -- 2 All born Perth.
Ann Nicol 77 Mother-in-Law b Schberman? Perthshire.
ScotlandsPeople has a death for an Ann Nicol, other name McDonald, age 85, 1879 at Perth.
Not what you were oiginally looking for, but a good find if it's the right person.
Regards, Dod.