Did Mary Ann marry again?
I don't think so. She's a widow on the 1939 register, living with her son at the same address as when her husband died, and there's not changes on the register to suggest she married after that date
Possible death? Basford is the district for most of the family's registrations
Mary A Walker
Age 81
Q4 1951
Basford Vol 3c, p51
Probate register: Mary Ann Walker, 62 Denison St, Beeston, died 15 Dec 1951