We just recently bought an older home that has a crane radiant baseboard heat system in it. It works great in all the rooms but 1. We traced the lines and it is the last room on the line for the hot water. Is there some way to adjust the heaters so that the last room stays warm too??

You will need to bleed that radiator/baseboard of air or
Find the zone valve/pump that is not working or
Raise boiler water temp to compensate for that area or
Re-pipe the zone to get a greater share of hot water to the area or
Buy a small electric space heater and forget about the problem.

If you choose the small electric heater you can plug that in yourself.
For all other fixes call a professional unless you know how to do the work.