Just a thought...

Try to narrow down the source of the problem.

It could be an individual circuit in the panel tha is faulty or a
combination of breakers that are creating an imbalance on the one leg
of the mainbreaker (although unlikely as I assume that it was working
before). However, to see if this problem is originating from the panel
in the mobile home, TURN OFF all the the breakers in the panel and then
try to reset the main breaker.

If the main breaker stays on, then try turning on circuit breakers in
the mobile one at a time to see when it trips the main.

If turning off all the breakers doesn't solve the problem with the main
breaker, then the problem might be some damage in the wiring from the
main breaker to the panel in the mobile. To check this try
disconnecting the cable that feeds the mobile from the main breaker and
just try setting it on its own. If it stays on then try reconnecting
the cable to the breaker, but reverse the red and black wires and see
if the breaker still trips.

The purpose of the main breaker that is tripping is to protect the wire
that is feeding the mobile home, so it is not usually an issue that is
being created by a problem between the meter and the main breaker.

Hope this information helps...