There is never any way to tell for sure how the folks at Medicaid are going to consider a particular set of transactions.
They could see the purchase of the property and subsequent transfer to your son as having been done without value and therefore a countable asset because it was a gift. There would be a 5 year look-back period -which may be extended to a 10 year period at some point.
They could also see the usufruct as something that has potential ongoing income value to you.
You really should consult with someone experienced in this area since it would be about an hour conversation exploring your exact financial position and the possible strategies that might be available.