Wooden floor to be replaced by concrete

You should check to see if there’s any ventilation bricks or breathers on the outside of the property if so make sure there not covered in dirt or shingle etc.

I wouldn't advise concreting. The issue with your damp has a lot to do with air flow, houses built in 1900 with suspended floors were meant to breathe. Ideally you need to check the air bricks/vents outside, check they are clear. A solution to this is to replace them, whilst they are out clear as much as the cavity between the outside brickwork and internal brickwork. It's worth looking under the floor and ensuring this is clear and free of debris, thus allowing air to flow under the floor. Sort the air flow problem first, if you continue to get damp then you may need a new damp proof course injected into the walls. With the age of the house it's a common issue with original damp proof course failing. Hope this helps

As previous answer would not recommend filling with concrete and sort out air flow

Normally the problem is air bricks or vents blocked with mud or leaves not allowing airflow under the floor causing build up of damp/ moisture . I have had to sort out a few of these in the past. Do not fill with concrete