Unable to link Robert Mumma to any other families, but he is clearly identified in the 1880 & 1900 census.
It would appear that he never fathered any children. I have not found he or his parents in the 1860 or 1870 census of any county in Pennsylvania.
His wife provided the information for his death certificate and she stated "unknown" for the names and location of birth for his parents. She stated his place of birth was Harrisburg.
1880 Census, PA, Cambria Co., Johnstown, Ward 4, ED 182, dwelling 164
Mumma, Robert, 26, married, barber, b: PA/PA/PA
" , Catharine, 35, married, wife, keeping house, b: PA/PA/PA
Homer, Martha J., 18, step dau., at home, b: PA/PA/PA
1900 Census, PA, Cambria Co., E. Conemaugh Borough, ED 182, p. 102, dwelling 301
Mumma, Robert F., head, Mar 1854, 46, m: 21 yrs, b: PA/PA/PA, merchant
" , Catharine, wife, Sept 1841, 58, m: 21 yrs, 1 child, 1 living, b: PA/PA/PA
Will Index of Cambria County, PA
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MUMMA, ROBERT F. EAST CONEMAUGH PA-11-8-51
Grandview Cemetery Interment Records
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http://grandviewjohnstownpa.com/interment-details.php?inter_no=7681
Interment Details
Inter. No.: 7681
First Name: R. FRANK
Last Name: MUMA
Lot: 196
Section: HI4
Interment Date: 6/10/1909
Date of Death: 6/7/1909
Place Deceased: CONEMAUGH, PA
Date of Birth:
Place of Birth: LANCASTER, PA
Age: 55
FindAGrave = Memorial #95700878
https://www.findagrave.com/cgi-bin/fg.cgi?page=gr&GRid=95700878