What type of HMM-GMM I need
Normally in speech-to-text we don't already have a perfect segmentation into words, which is why we often use the HMM to match the entire speech sentence.  Also, this way the HMM can take into account probabilistic information on the distribution of word bigrams (and even trigrams).  If you already have a segmentation and you are sure it is correct, then you can use the HMM to match just the word, if you like.  But getting a reliably correct segmentation is tricky, given how people speak in practice, so you might want to check how accurate your segmentation is before relying upon it.

Either GMM + HMM or DTW would be a reasonable approach.

A very simple approach would be to download an existing speech-to-text tool and use it on those sentences, instead of trying to build something yourself.