The most effective means of limiting the damages, that are caused by rodents is rodent-proof construction. Since, your house is about 100 years old,you can mix broken glass or steel wool in with cement to seal the hole or an opening, from where the rats enter your basement.For this, first of all, you will have to locate the entry points to seal them. If you don't like to spend much on it, you can at least try of using Concrete crack injection to fill up the cracks and holes.