What options exist it any, for a radiation resistant, transparent, and durable material that could theoretically be used for a ceiling of a martian dome?
85% as hard as sapphire, 80% transparent to Visible Light, used as Bulletproof glass capable of stopping multiple 50 cal rounds. Capable of withstanding temperatures up to 2100°C, radiation resistant and resists damage from water and most acids or bases.
It is transparent to near-infrared and mid-infrared (but not to UV), so you might require an extra coating on the inside to block that (Transparency range is about 200–5000 nm)
Water ice could be used. It would need a membrane plastic coating on the outside to prevent sublimation and an inner plastic or glass inner panel to help with temperature regulation. But several metres of ice would provide significant radiation protection and the weight would help to contain the high pressure within the dome. If impurities are removed ice can easily be frozen into a very clear blocks. Water us available on Mars in large quantities and would be required at the first Mars base for ISRU propellant production, as well as a source of drinking water and oxygen.