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Having everyone here with me is more reassuring to me than the police or anything else.
Literal
I [to-には] police [than-よりも] anything [than-よりも] everyone [subject-が] be-for-me [genitive-の] thing [genitive-の] side [subject-が] reassuring [explanatory-のです][assertive-よ].
An emotional declaration. The comparative frame is a triple-stacked ~より: 警察よりも何よりも, literally 'more than the police, more than anything.' The second より intensifies the first, producing an 'above everything else' effect. みんながいてくれること uses the ~てくれる pattern ('exist for me / be present on my behalf') and nominalizes the whole with こと. ~の方 ('the side of X,' 'as for the X option') is a comparative particle that picks one side of a comparison as the winner — 'the X side is more Y.' The ending のですよ lends declarative warmth, as if the speaker is gently explaining their heart.