After looking at the image myself, I believe the middle image definitely looks more like a 'G' than a 'M' to me, although it looks very faint, but you can see a faint trace of the top of the 'g'.
Hannah Gertrude Bettany was born 1895 - she would be 6 on the 1901 census
Annie Maria Bettany was born 1893 There was also another Annie Maria Bettany born 1890 in Cheadle.
I would conclude that both Hannah and Annie were on the census. I think maybe the enumerator wrote it down wrong- as this records them both as Hannah. I think they wrote Annie as Hannah and recorded the initials wrongly.