What are the implication of extracting tooth #17 without restoration and implants? Will wearing mouth guard at night prevent super eruption and tooth swaying? I cannot afford bone graft or implants. If you were in my situation. What would you do?

Great Question. If I were in your situation, I would have # 16 extracted too and never again worry about wisdom teeth on my left side. Regarding bone grafts and implants for # 17, save your money for more important expenditures.
Good question. Removing number 17 should not impact any of your other teeth significantly. Since it's a terminal or last tooth in the mouth there should be no consequences to the adjacent teeth. The opposing teeth could be affected in a minor way. It all depends on the position of all of your teeth and how they come together. Your dentist will be your best guide for proper short and long-term care.
Disaster. Disaster waiting to happen. Opposing wisdom tooth (#16) will over ups and adversely affect occlusion, and may cause TMJ. Not efficient to replace lower wisdom tooth. Have both upper & lower removed at same time. See Oral Surgeon for consultation. Consider giving up your internet connection for a month or two to fund your health care needs.
? #16. No risk for tooth movement in lower arch. If #16 is erupted, then it might super erupt , but this may also be removed at same time as #17. Ask Oral Surgeon about removing both at same time - best option. Good Luck.
Oral surgeon consult. This is a third molar. Speak with the dentist or oral surgeon and see if all third molars need to be addressed and the positioning of tooth #16, if it is viable and would leaving the tooth lead to super eruption or is it in occlusion.
Extract #16 and #17. If you have a full arches of teeth, removing wisdom teeth #16 and #17 would not cause any issue at all. That can help you avoid problems in the future.
Dental exam. and x-ray will help diagnose your current condition. Please see a dentist. It is important to have a clean oral environment before surgery esp if there's presence of periodontal disease. .