Which shows the correct word and standard forms for the decimal?
20 + 6 + 0.09
a.
twenty-six and nine tenths
26.9
b.
twenty-six and nine hundredths
26.09
c.
twenty-six and nine hundredths
26.9
d.
twenty-six and nine thousandths
26.009
is it b?

Yes, it is B.
In a decimal, the naming goes tenths, hundredths, thousandths, and so on.

0 . 0 0 0
First 0 (in front of decimal point) is the ones place.
Second 0 is the tenths.
Third 0 is the hundredths.
Fourth 0 is thousandths.
Adding the 3 numbers together in your example, we get 26.09.
Since the 9 is in the hundredths place, we say "twenty-six and nine-hundredths"