Our renters are demanding we finish an unfinshed basement do we have to?

We are in Nv. We are currently renting out our old home it has 3 bedrooms upstairs, and 2 full bathrooms. Downstairs is a unfinished 1/2 bath it does a a functioning sink and toilet, there is no sheet rock. The water heater and the furnace are both located in the bathroom. They are claiming it is a health and safety issue and are threatening to sue if not fixed. There is 2 finished bedrooms and a family room downstairs as well. We had propane installed in the home to help with the heating bills and needed to leave a small portion of the ceiling unfinished to accomadate the new materials needed to bring in propane heat. They also want that fixed. The home was built in 1974-75. When we bought the homw 6/7 years ago the basement had nothing we added carpet, sheetrock, and the ceiling but moved before the bathroom and the ceiling got fininshed. They want all this fixed within 14 days of the letter with their 10 demands met or they are threating to withhold rent, repair and deduct the cost to fix it to their specifications, which leaves us paying the rent, terminate their agreement or sue us. We are using a property manag er to handle the property and we have agreed that termination would be best for all, well except for the tenants they want everything up to current building codes which will cost us financial hardship. Are we required to do any of their demands? Any advice would help! Please and thank you.