To achieve your financial goals while managing your current liabilities, we will focus on a balanced approach that aligns with your moderate risk tolerance. Considering your desires to buy a house, save for children's education, and prepare for retirement, here's a comprehensive investment strategy tailored to your situation:

### Investment Strategy

1. **Monthly Surplus Utilization:**
   - **Total Monthly Surplus:** ₹50,000  
   - **Debt Repayment:** Allocate ₹20,000 monthly to pay off your outstanding debt of ₹100,000. This will allow you to become debt-free in 5 months. After resolving this, you will have more disposable income available for savings and investments.

2. **Emergency Fund:**
   - Prioritize setting aside ₹25,000 in a high-interest savings account to serve as your emergency fund, covering around 5 months of expenses. This will provide a safety net for unexpected expenses.

3. **Investment Allocation After Debt Repayment:**
   - Once the debt is cleared, you can redirect the ₹20,000 previously allocated to debt repayment into investments along with your regular saving.

4. **Investment Options:**
   - **Mutual Funds and ETFs:** 
     - Focus on a mix of Index Funds and Equity-oriented Mutual Funds for long-term growth, considering your moderate risk appetite. Suggested allocation:
       - 60% in equity index mutual funds (SIP of ₹12,000)
       - 30% in balanced or hybrid mutual funds (SIP of ₹6,000)
       - 10% in debt or liquid funds to keep liquidity (SIP of ₹2,000)

5. **Goal-Based Monthly Savings:**
   - **Buy a House:**  
       - Target: ₹1 Crore in 5 years. You need to save approximately ₹16,667 monthly. Given your surplus capacity post-debt clearance, redirect ₹8,000 monthly into a mutual fund focused on real estate or a mix of large-cap equity to target growth over this course.
   - **Children's Education:**  
       - Target: ₹20 Lakhs in 14 years, requiring approximately ₹11,905 monthly. With your adjusted monthly investment strategies post-debt clearance, you can allocate ₹6,000 monthly into an aggressive growth fund or a child education plan.
   - **Retirement Savings:**  
       - Target: ₹4 Crores in 25 years, suggesting around ₹10,000 monthly at baseline. Post all adjustments and assuming debt is paid, you could focus on contributing the remaining balance towards compounding through equity mutual funds, ultimately targeting an additional ₹6,000 monthly after settling all priorities.

6. **Monitor and Reassess:**
   - Every 6 months, evaluate financial goals and performance of investments. Adjust allocations if returns are falling short or if you have risk tolerance changes due to market dynamics.

### Insurance Recommendations
- **Life Insurance:** Acquire a term insurance policy equivalent to your liabilities (approximately ₹1 Crore) in case of unforeseen circumstances.
- **Property Insurance:** Once you purchase a house, ensure to get comprehensive insurance covering both property and personal liability to protect your investment.

### Assumptions Made:
- Investment returns are assumed to be approximately 10-12% annually for equity and 7-8% for debt instruments, which is conservative yet achievable based on market trends.
- No current investments were disclosed, thus this strategy does not involve liquidating existing assets.
- The rate of debt interest has not been specified; thus strategic debt pay-off was prioritized based purely on existing figures.

This structured investment strategy seeks to balance savings towards your important life goals while mitigating risks and ensuring a path towards financial security. Adjust your contributions over time as your financial situation evolves.