"most", note the suffix -est, is a superlative. That's its form, and it's either introduced by "the", a definite article, or followed by "of all", which is also defining:
I like her the most.
I like her most (of all).
"of all" is often omitted, which is probably why "most" was not as common as "the most" in your search.
I use both forms.In addition, is it true the native speakers tend to use "the best" in this pattern when the object is a person? For example "I like my mother the best." is more preferable to "I like my mother the most."?