"It is a CA client'

Then IRS research won't be useful, if your question relates to CA taxes.

"and it was declared a federal disaster. Does that change anything?"

It depends on the breakdown of the settlement. It will matter if some is identified as settlement for physical injury, punitive award, replacement.

"I am thinking she has 4 years to replace the property from the date of the settlement. Is that correct?"

Are you using web resources to find applicable info for CA and/or Fed? Example:

https://lamalfa.house.gov/pge-wildfire-settlement-payments-general-information

"Generally, you must purchase replacement property within two years after the end of the year in which your property was destroyed, or within four years after the end of the year in which your property was destroyed if the property is in a Federally declared disaster area. You may apply for an extension of this period under procedures described in IRS guidance."

If this is a Fed question, Pub 547 for the tax year in question, is a great place to start.