@sandrabaca124. I'm sorry for your loss.
I'm assuming that you are renting out the house that you inherited and therefore need to figure out the land value for depreciation purposes because land is not depreciable.
The best way is to use the value given by a licensed real estate appraiser who you hired to give you a written appraisal of the property value as of the date of death. That is likely to be the most correct.
Other possibilities would be to use the town real estate assessment from that time. Since many town assessments are not accurate if the total doesn't reflect the date of death fair-market value (FMV) you might apply the % of land to your FMV value. E.g. assessment $250k, land $50k. $50/250 = 20%. So land value might be 20% x $330k. But that is not strong documentation and if questioned the IRS may or may not accept that.
I think you also know that your basis in inherited property is usually the FMV as of the date of death. This does not apply if your mother transferred any part of the house to you before she died.
How did you determinate the $330k valuation?
Check with the local Tax Assessor's office for a breakdown of the value of your mother's former house (land vs improvements) .
They may only be able to provide a typical ratio of the value of land/improvements, but that will allow you to come up with a value for the land and the improvements (the house).
This screenshot from the IRS Depreciation Frequently Asked Questions gives an example on how this formula works: