Question about relocation/termination rights

My position at a high tech company is being relocated to another state (From CA to TX), and I've been offered a full relocation benefits package. However, I don't have the means to relocate (just purchased a house 6 months ago, all my family is local to me now) and was given the alternative of working through the end of the month and then provided with 2 months of severance. I was told this on March 1 in the afternoon, given until March 15 to let them know of my intentions, and if not moving will have my last day in the office March 30. I understand severance is not a right, but is the amount of time (29 days) they've provided me legal to find something else, or is that part of the severance? The relocation is only affecting 2 total employees.