Yes... almost every possible answer has been provided. From anti-slip rubber mats, sprays to grab bars.
This is a serious situation. A person known to me died instantly after he slipped and fell on a bottle kept in the corner of the bath. Sadly he landed on the bottle on the back of his head.
Keep the bath floor dry as far as possible. Also switch to liquid soap of gel in the interim. Soap bars have a greater tendency to slip because when the soap bar falls on the floor it leaves soap residue. Also use an anti grease when mopping the bathroom floor. These are normally slightly acidic (or even pH neutral) cleaners.
Another effective solution is the usage of anti slip treads. Simple and effective. These are removable self adhesive strips. 3M used to produce quality treads called Safety-Walk. These are clear. 2 inch wide strips which you can cut and stick to the floor.