Modification of home loan requires access?

I have an A.R.M. that has skyrocketed. I informed the lender that I was in need of a loan modification or else I would be forced to let it go into foreclosure (which I don't want). Today I received a letter with an attached form called "Exhibit D." This is also titled "Authorization To Access Property." It gives the lender and/or its "agents" the right to come in and do an inside "market appraisal for consideration for a loan modification." I don't know if this is leagl mumbo jumbo, a trick or a legit thing. Any help?