I came across your post and think I can help. There is an Ormsby Road in Bonsall off of Vista Way. I am pretty sure this is named after the family you are looking for. The area is well known for it's ability to support the growing of subtropical fruits. There was a famous nursery called M&N Nursery off of Ormsby Road for many years that supplied the area with subtropical fruit plants. The Oceanside, Vista, and Carlsbad area had many avocado groves in the 1930's and 1940's until the soil became infested with root rot and land became more valuable for housing. Subsequently many of the growers moved inland to Fallbrook etc. I would suggest contacting the Vista Historical Society for more help. Keep in mind though that Bonsall is an unincorporated area of San Diego county so less history will have been kept and be available.