Best way is first go to regular gandhi park bus stand. Since it is adjacent to railway station second entry GT road side. & Its morning time may be traffic is not diverted.
After that if you don't find bus then ask at bus station enquiry about mathura buses going from सूत मील .
Its easy to commute to 3rd bus station you can go via electric city bus frequency ever 15 minutes which stops just opposite to the Gandhi park bus stand.
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more... Or hire a auto if going with family.
Anyhow if you get confused people or shop keepers at bus stand or outside railway station will guide you. (Remember you are in middle of the city)