I also posted this and another message in response to your query on the ancestry message board.
I found this John Stevens in the 1860 Census, but there was no wife listed with him and there were no children listed with him. It looks as though he was a single person living with Patrick Burns and his family. Name: John Stevens Age in 1860: 31 Birthplace: Ireland Home in 1860: Lafayette, Tippecanoe, Indiana Gender: Male Value of real estate: Post Office: Lafayette Roll: M653_300 Page: 779 Year: 1860 Head of Household: Patrick Burns
Next I found a marriage for Eliza Murdock and John Stevens
Marriage Date: 02 Dec 1860 County: Tippecanoe Book: C-9 Original Source Page: 284
A lot of times, if you write to the county giving them the book and page, they will send you a copy of the marriage record for a nominal charge. You might find the father's name on the marriage bond or license.
I did not find any Murdocks born in Ireland in Tippecanoe County, Indiana in the 1860 Census that fit your family.
In the 1870 Census, I found a Murdock family Name Age in 1870 Estimated Birth Year Birthplace Race Home in 1870 (City, County, State) Gender
James Murdock 34 1835 Ireland White Lafayette Ward 1, Tippecanoe, IN Male Johanna Murdock 29 1840 Ireland White Lafayette Ward 1, Tippecanoe, IN Female Charles 5 1865 Indiana White Lafayette Ward 1, Tippecanoe, IN, Male Samuel 3 1867 Indiana White Lafayette Ward 1, Tippecanoe, IN, Male John Murdock 32 1837 Ireland White Lafayette Ward 1, Tippecanoe, IN Male Thomas Murdock 30 1839 Ireland White Lafayette Ward 1, Tippecanoe, IN Male sibba Murdock 72 1797 Ireland White Lafayette Ward 1, Tippecanoe, IN Female
Johanna is James' wife and "sibba" is listed as "mother." I wonder if this might be "Libba" instead. This information is found on Roll: M593_362 Page: 53
In the 1880 Census, I did not find John Stevens indexed for some reason, but I found Name: Eliza STEVENS Age: 63 Estimated birth year: <1817> Birthplace: IRE Occupation: Keeping House Relation: Wife Home in 1880: La Fayette, Tippecanoe, Indiana Marital status: Married Race: White Gender: Female Head of household: John STEVENS Father's birthplace: IRE Mother's birthplace: IRE Cannot read/write: Blind: Deaf and dumb: Otherwise disabled: Idiotic or insane: Year: 1880; Census Place: La Fayette, Tippecanoe, Indiana; Roll: T9_314; Family History Film: 1254314; Page: 270C; Enumeration District: 27
I hope this helps.
The following is my second reply on the ancestry message board.
I think I found the same Murdock family I found in the 1870 census in the 1860 census. It was indexed under Murdick instead of Murdock.
Name: Samuel Murdick Age in 1860: 33 Birthplace: Ireland Home in 1860: Wabash, Tippecanoe, Indiana Gender: Male Value of real estate: Post Office: Lafayette Roll: M653_300 Page: 643 Year: 1860 Head of Household: Samuel Murdick
Samuel Murdock 33 M Farmer Ireland Sally Murdock 62 F Widow Ireland James " 24 M Farmer Ireland John " 21 M Farmer Ireland Thomas " 20 M Farmer Ireland Eliza Clark 31 F Domestic Ireland Ellen " 9 F Ireland
It looks to me like Eliza was married before she married John Stevens unless she is not related to this Murdock family and just hired help. Considering the information you gave, I think she was the older sister. As for the mother's name, I cannot figure that out - they are the same age and they start with the same letter but the other letters do not match. This one is definitely Sally and the other one really looks like Sibba.
Name: John Stephens Age in 1870: 50 Estimated Birth Year: 1819 Birthplace: Ireland Home in 1870: Lafayette Ward 1, Tippecanoe, Indiana Race: White Gender: Male Value of real estate: Post Office: Lafayette Roll: M593_362 Page: 73 Year: 1870
Stephens, John 50 M W Ireland Eliza 39 F W Ireland James 15 M W Indiana John 13 M W Indiana Sarah 9 F W Indiana Mary 6 F W Indiana Elizabeth 4 F W Indiana The age isn't right for Eliza, but on the other hand, they have a daughter, Sarah, and Sally is a nickname for Sarah. Unfortunately, Ellen is not listed with this family, but that may have been because she married. I did find a marriage record for Elijah Cockrell and Ellen Clark Marriage Date: 07 Jun 1867 County: Tippecanoe Book: C-11 Original Source Page: 421
Again, I hope this information helps you in your research.