What would drive the dynamo would depend on what the electricity was being used for. The three main options would be (a) a steam engine, (b) an oil engine, and (c) a petrol/gasoline engine. A diesel engine would be possible but unlikely; commercial diesel engines were very new in 1899-1900.

If the electricity was only being used for lighting, it's quite possible that the dynamo would only be operated in the early morning and in the evening (when demand for lighting was greatest). For this kind of relatively short-term operation, a petrol engine is good. Modest lighting for a dozen buildings might use under 3kW, and this could be met by a petrol engine of the time.

An oil engine would also suit this lighting task, and has advantages: oil engines are reliable and long-lasting, and the fuel is safer to transport and store. High-power oil engines were available, and could handle electricity generation tasks that required more power (e.g., bright outdoor lighting of the compound, powering electric motors, etc.).

If the demand for electrical power was all-day, so that the dynamo would be run for 24 hours, a steam engine would be a good option. For off-on use, a steam engine is usually a poor choice, due to the time taken and energy used to heat the water in the boiler, to get to operating pressure. For constant use, this isn't a problem, and steam engines, typically steam turbines by the end of the 19th century, were commonly used for electricity generation.

Thus:

1. For short term, low-power off-on generation: petrol/gasoline engine, or small oil engine.

2. For longer term or higher power off-on generation: oil engine.

3. For 24 hour operation: steam engine, probably a steam turbine (an oil engine could also be used).