Aged 50 on 1841 census (rounded)

If died in W Bolton in 1848, aged 54, then born 1794

Lancashire Death indexes for the years: 1848
MATHER    Thomas    54    Western Bolton    Bolton    WB/13/341

Name:    Thomas Mather
Age:    54
Birth Date:    abt 1794
Burial Date:    12 Nov 1848
Burial Place:    Deane, St Mary, Lancashire, England
Reference Number:    GB127.L85/1/4/6

Abode: Great Bolton

Aged 36 years

11 in 1841
21 in 1851, born Great Bolton
31 in 1861, born Bolton
41 in 1871, born Bolton
51 in 1881, born Bolton
57 in Oct 1887 when died

Maria (or Mary) would have to be born after Oct 1829 and before April 1830 for all dates to match her age.

No baprism for Maria in Bolton, but baptism for Mary in 1829 is the only one within 2 years of 1830, and she is daughter of Thomas and Margaret.
Name:    Mary Mather
Gender:    Female
Baptism Date:    10 May 1829
Baptism Place:    Saint Peter,Bolton,Lancashire,England
Father:    Thos. Mather
Mother:    Margt.
FHL Film Number:    942.72 B3V26BV. 17-23

Name:    Maria Fogg
Estimated Birth Year:    abt 1830
Registration Year:    1887
Registration Quarter:    Oct-Nov-Dec
Age at Death:    57
Registration district:    Ashton Under Lyne, Lancashire
Volume:    8d
Page:    398