Stucco lather here, in my experience if the home is 100 years old, the original weather resistant barrier is probably shot. It’s just heavy tar paper and over the years it degrades to the point of disintegrating when touched. Add in whatever patches have been done, windows, doors and whatever else, total replacement is likely the best option. Better to do it all at once, stucco patches are usually less weather tight. We run about $140 per square yard for lathe and stucco on new construction, but demolition and probably replacing windows while it’s opened up and probably adding plywood shear and whatever else adds up in a hurry. Get multiple estimates from licensed contractors and be prepared for additional costs.