<BuildingModifiers>
<Row>
<BuildingType>BUILDING_MONUMENT</BuildingType>
<ModifierId>MONUMENT_GRANT_OIL</ModifierId>
</Row>
</BuildingModifiers>
<Modifiers>
<Row>
<ModifierId>MONUMENT_GRANT_OIL</ModifierId>
<ModifierType>MODIFIER_SINGLE_CITY_GRANT_RESOURCE_IN_CITY</ModifierType>
</Row>
</Modifiers>
<ModifierArguments>
<Row>
<ModifierId>MONUMENT_GRANT_OIL</ModifierId>
<Name>ResourceType</Name>
<Value>RESOURCE_OIL</Value>
</Row>
<Row>
<ModifierId>MONUMENT_GRANT_OIL</ModifierId>
<Name>Amount</Name>
<Value>1</Value>
</Row>
</ModifierArguments>
This is the solution for what you are looking for, for testing purpose i attached the modifier to the Monument Building, and it is working.
you would have to replqce BUILDING_MONUMENT with your building type
and maybe rename the modifier MONUMENT_GRANT_OIL to something more fitting (like OILCOMPANY_GRANT_OIL)
so in shot: for every effect you want like this you need to:
1) create a modifier with the type you need , done in <Modifiers>
2) give that modifier its arguments, done in <ModifierArguments>
3) attach that modifier to your building, done in <BuildingModifiers>