I cannot find Isaac in either 1850 or 1860.

Her death certificate records Mahalia Sorrell, age 79 years 27 days, born 21 Dec 1834 in Rowan Co., died 18 Jan 1918 in Farmers, Rowan Co., Ky, widow, father David Bradshaw, born in Va, mother’s maiden name Marine Myers, born in Ky, cause of death paraplegia, informant W. S. Sorrell, Farmers, Ky, burial in Slaty Point.

The birthdate is very wrong, since she was listed as age 8 in 1850, age 23 in 1870, and age 38 in 1880. (I have not found her in 1860.) The reported age at death would imply a birthdate in 22 Dec 1838. I think she was probably really born in either 1840 or 1841.

The marriage date of about 1864 is based on the age of their oldest child (Joseph) in the 1870 census. However, I cannot find either Isaac or Mahala in the 1860 census, so it is possible they were already married by then, and that any children they had before 1865 died young.

1870 census of Rowan Co., Ky, Pearce precinct, p. 127B, lists as family #82:
Sorrell, Isaac, 25, saw mill hand; Mahala, 23; Joseph, 5; Caleb, 3; Edgar, 1. All born in Kentucky.

1880 census of Rowan Co., Ky, precinct #2 (Licking City and Cross Roads, aka Farmers), lists as family #169:
Sorrel, Isaac, 37, laborer; Haley, 38; James H., 16; Marcus K., 13; William E., 11; Lucretia F., 9; Luvena, 9; Cora A., 6; Tamsy A., 2. All born in Ky.

The son listed as James H. is probably really Joseph Henry.

1900 census of Rowan Co., Ky, Farmers precinct, enumerated 22 June, lists on p. 25 as family #343/346:
Sorrell, Mahala, head, farmer, 59, b. Dec 1830; Wm E., son, 31, b. Feb 1869; Lucrecia, daughter, 29, b. Apr 1871; Cora, dau, 27, b. Oct 1872; Winfield S., son, 18, b. Aug 1881; Mary D., dau, 18, b. June 1881. (The last two entries make no sense together at all. Two children of the same mother cannot be born 2 months apart. The reported age and birthdate for Mahala are also not consistent with each other, since a birth in Dec 1830 would mean she was 69, not 59.)

1910 census of Rowan Co., Ky, Farmers precinct, enumerated 14 May, lists on p. 20B as family #345/352:
Sorrell, Mahala, 69, widowed, mother of 10 children, 7 living, farmer; William E., son, 41, single; Lucretia F., dau, 39, single; Cora A., dau, 37, single; Roberts, Edna, ward, 7. All born Ky Ky Ky.

1920 census of Rowan Co., Ky, Farmers precinct, enumerated 2 Jan, lists on p. 1B as family #16:
Sorrel, Lucresie, 42; Edgar, brother, 37; Cora, sister, 29. All born Ky Ky Ky.

The ages are very wrong. Judging by earlier censuses, Lucretia should be 47, Edgar 51, and Cora 46.