$ cat 1.txt
'&1'
'&2'
'&3'

:1
:2
:3

awk '{gsub(/'"^'"'|'"'$"'/,"");gsub(/&/,":")}1' input
:1
:2
:3

sed -e 's/.*[^0-9]([0-9]+)[^0-9]*$/:1/' 1.txt

:1
:2
:3

$ cat 1.txt
Monday {'&1', 'Morning', 'Breakfast'}
Tuesday {'&2', 'Noon', 'Lunch'}
Wednesday {'&3', 'Evening', 'Supper'}
Thursday {'&4', 'Night', 'Dinner'}

$ sed -E 's/x27&([0-9]+)x27/:1/' 1.txt
Monday {:1, 'Morning', 'Breakfast'}
Tuesday {:2, 'Noon', 'Lunch'}
Wednesday {:3, 'Evening', 'Supper'}
Thursday {:4, 'Night', 'Dinner'}