My tenant complains of moisture under their bed and child's crib. The room as ceramic tile floor - probably laid on cement. I gave them a dehumidifier that seemed to help but not that it is hot they complain it is too hot to run de humidifier. What else can I do?

I'm guessing there is not a central ac in the house which would eliminate the problem unless its not being used. In this case why not try an oscillating fan together with the dehumidifyer to cool and circulate the air. If the dehumidi is creating that much heat though you should look into other models that don't. Aside from those options you might try to find a Desiccant that would fit your situation like the gel packets used in packages to elimate moisture but on a larger scale.

A dehumidifier should not be contributing heat to the room. Assuming that this is a ground floor concrete slab, unless there is a bathroom nearby that could be leaking you have a leaking supply pipe underneath the floor. If the floor is warm to the touch it is a hot water pipe. You probably should call a pro to find and repair the leak. Sugnificient damage can occur if left unattended.