If a 43-year-old man dies can his 86 year old mother receive his Social Security survival benefits?

Only if she was his legal dependent, i.e. she would have to meet all the qualifications that the IRS requires. Very few could met the qualifications. You would need to provide more information about support and income before the question could be answered.

I don't think her son's SS would provide her any benefits. My guess is his mom receives SS already. At age 43, even if his SS benefits could be applied to her they might be less than what she is receiving now. On the whole, however, I don't think his mom would qualify as a dependent. You should probably call SS and ask this question. Good luck, Cattails